From 99672791e9c9f56257075ad95c285f03a6309720 Mon Sep 17 00:00:00 2001
From: Pavel Shpakovskiy <pashpakovskii@salutedevices.com>
Date: Sat, 8 Aug 2026 19:31:11 +0300
Subject: Bluetooth: mgmt: fix 'hdev->discovery.uuids' NULL dereference

'uuid_count' member of struct 'discovery_state' is assigned and read
without any locks, so there is a chance of situation when
uuid_count != 0, but uuids is NULL and there will be NULL pointer
dereference.

Possible race:
'hci_update_passive_scan_sync'
  'hci_discovery_filter_clear'
    hdev->discovery.uuid_count = 0;
      <----------------------preempted----------------------------->
                        'start_service_discovery'
                          // Set uuid_count to value != 0
                          hdev->discovery.uuid_count = uuid_count;
                          hdev->discovery.uuids = kmemdup(...);
      <----------------------preempted----------------------------->
    spin_lock(&hdev->discovery.lock);
    kfree(hdev->discovery.uuids);
    hdev->discovery.uuids = NULL;
    spin_unlock(&hdev->discovery.lock);

Now uuids == NULL and uuid_count != 0.
So 'mgmt_device_found' -> 'is_filter_match' -> 'eir_has_uuids' receives
non consistent discovery state, where NULL dereference of uuids happens.

To fix it let's add discovery.lock around every read/write of uuid_count,
uuids pair of struct members. It is also important to assign uuid_count
value only after success kmemdup() allocation in
start_service_discovery(), otherwise uuids is NULL, because kmemdup failed,
but uuid_count is already assigned to non zero value.

The following panic happens:

[ ] ------------[ cut here ]------------
[ ] Unable to handle kernel NULL pointer dereference at virtual
address 0000000000000000
[ ] Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
[ ] CPU: 0 PID: 15056 Comm: kworker/u9:2
[ ] Workqueue: hci0 hci_rx_work
[ ] pstate: 10400009 (nzcV daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ ] pc : eir_has_uuids+0x2d8/0x590
[ ] lr : is_filter_match+0x258/0x320
...
[ ] Call trace:
[ ]  eir_has_uuids+0x2d8/0x590
[ ]  is_filter_match+0x258/0x320
[ ]  mgmt_device_found+0x5b0/0xafc
[ ]  process_adv_report.part.0+0x8c8/0xf14
[ ]  hci_le_adv_report_evt+0x338/0x3f0
[ ]  hci_le_meta_evt+0x1f0/0x4c8
[ ]  hci_event_packet+0x440/0xc9c
[ ]  hci_rx_work+0x44c/0xaf8
[ ]  process_one_work+0x54c/0x103c
[ ]  worker_thread+0x6c4/0x10c4
[ ]  kthread+0x274/0x2ec
[ ]  ret_from_fork+0x10/0x20
[ ] Code: 14000004 91004021 eb14003f 54000180 (f9400024)
[ ] ---[ end trace 0000000000000000 ]---

Fixes: 2935e556850e ("Bluetooth: hci_sync: fix double free in 'hci_discovery_filter_clear()'")
Signed-off-by: Pavel Shpakovskiy <pashpakovskii@salutedevices.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/hci_core.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'include')

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index e07418a5adce..4105c446ca98 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -935,9 +935,9 @@ static inline void hci_discovery_filter_clear(struct hci_dev *hdev)
 	hdev->discovery.result_filtering = false;
 	hdev->discovery.report_invalid_rssi = true;
 	hdev->discovery.rssi = HCI_RSSI_INVALID;
-	hdev->discovery.uuid_count = 0;
 
 	spin_lock(&hdev->discovery.lock);
+	hdev->discovery.uuid_count = 0;
 	kfree(hdev->discovery.uuids);
 	hdev->discovery.uuids = NULL;
 	spin_unlock(&hdev->discovery.lock);
-- 
cgit v1.2.3


From d67f4a43e7ef8cff8aa8fe1df2f088390af41b6d Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sat, 8 Aug 2026 12:08:45 +0300
Subject: Bluetooth: L2CAP: fix race l2cap_sock_cleanup_listen() vs. put_chan

For L2CAP sockets without owning sk->sk_socket, reading
l2cap_pi(sk)->chan may race against concurrent l2cap_sock_kill() ->
l2cap_sock_put_chan().  This excludes simultaneous proto_ops callbacks,
but access in l2cap_sock_cleanup_listen() has unsafe lockless read.

 [Task 1]                         [Task 2 (hdev->workqueue)]
 l2cap_sock_release(parent)       l2cap_disconn_cfm
   l2cap_sock_cleanup_listen        l2cap_conn_del
     bt_accept_dequeue                l2cap_chan_del
       lock_sock(sk)                    l2cap_sock_teardown_cb
       bt_accept_unlink
         bt_sk(sk)->parent = NULL
       release_sock(sk) ----------------> lock_sock(sk)
                                          parent = /* NULL */
     lock_sock(sk) <--------------------- release_sock(sk)
                                          sock_set_flag(sk, SOCK_ZAPPED)
                                      l2cap_sock_close_cb
                                        l2cap_sock_kill(sk)
                                          l2cap_sock_put_chan
     chan = READ l2cap_pi(sk)->chan         l2cap_pi(sk)->chan = NULL
     l2cap_chan_hold_unless_zero            l2cap_put_chan(chan)
       kref_get_unless_zero(&chan->ref)

Task 1 may observe NULL which causes null-ptr-deref.

Fix the race by taking lock_sock() in l2cap_sock_kill() to
synchronize with l2cap_sock_cleanup_listen().  hold_unless_zero() is not
needed here, l2cap_pi(sk)->chan owns reference if it is non-NULL.

Clarify code comments vs. locking.

Fixes: 6fef032af009 ("Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()")
Reported-by: syzbot+e6382a2f53f5fc7453ac@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=e6382a2f53f5fc7453ac
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h |  5 +++++
 net/bluetooth/l2cap_sock.c    | 23 +++++++++++++----------
 2 files changed, 18 insertions(+), 10 deletions(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index ef6ce1c20a4f..3d9a32094347 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -699,7 +699,12 @@ struct l2cap_rx_busy {
 
 struct l2cap_pinfo {
 	struct bt_sock		bt;
+
+	/* With owning sk_socket chan may be read without lock, other access
+	 * should hold lock_sock.
+	 */
 	struct l2cap_chan	*chan;
+
 	struct list_head	rx_busy;
 };
 
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 8bf35bc8126f..1194c37e466f 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1344,7 +1344,12 @@ static void l2cap_sock_kill(struct sock *sk)
 
 	BT_DBG("sk %p state %s", sk, state_to_string(sk->sk_state));
 
+	/* Take lock to synchronize against access without owning sk->sk_socket,
+	 * eg. in l2cap_sock_cleanup_listen(). proto_ops etc. don't need lock.
+	 */
+	lock_sock(sk);
 	l2cap_sock_put_chan(sk);
+	release_sock(sk);
 
 	/* Kill poor orphan */
 	sock_set_flag(sk, SOCK_DEAD);
@@ -1548,14 +1553,10 @@ static void l2cap_sock_cleanup_listen(struct sock *parent)
 	 * establish sk_lock -> conn->lock and invert the established
 	 * conn->lock -> chan->lock -> sk_lock order (lockdep deadlock).
 	 *
-	 * Instead, briefly take the child sk lock to fetch and pin its chan.
-	 * l2cap_conn_del() reaches the chan free only via
-	 * l2cap_chan_del() -> l2cap_sock_teardown_cb(), which itself takes
-	 * the child sk lock; holding it across l2cap_chan_hold_unless_zero()
-	 * therefore guarantees the chan cannot be freed while we read and
-	 * pin it (hold_unless_zero() additionally skips a chan already past
-	 * its last reference).  We then drop the sk lock before taking
-	 * chan->lock, so sk and chan locks are never held together.
+	 * Instead, briefly take the child sk lock to synchronize vs.
+	 * l2cap_sock_kill that puts l2cap_pi(sk)->chan. We then drop the sk
+	 * lock before taking chan->lock, so sk and chan locks are never held
+	 * together.
 	 *
 	 * Since we cannot call l2cap_chan_close() without conn->lock,
 	 * schedule l2cap_chan_timeout to close the channel; it already
@@ -1565,10 +1566,12 @@ static void l2cap_sock_cleanup_listen(struct sock *parent)
 		struct l2cap_chan *chan;
 
 		lock_sock_nested(sk, L2CAP_NESTING_NORMAL);
-		chan = l2cap_chan_hold_unless_zero(l2cap_pi(sk)->chan);
+		chan = l2cap_pi(sk)->chan;
+		if (chan)
+			l2cap_chan_hold(chan);
 		release_sock(sk);
 		if (!chan) {
-			/* l2cap_conn_del() already tearing this child down */
+			/* Already torn down */
 			sock_put(sk);
 			continue;
 		}
-- 
cgit v1.2.3


From f4fe51177b82176080035025754d89f8e730f72f Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sun, 16 Aug 2026 13:26:21 +0300
Subject: Bluetooth: hci_core: add lockdep check to hci_conn lookups

Add lockdep check for RCU || hdev->lock in hci_conn_hash lookups that
return hci_conn pointer, as dereferencing that without locks can be
TOCTOU issue. It used to be several callsites did not hold appropriate
locks.

The check is equivalent to removing rcu_read_lock() and doing instead
list_for_each_entry_rcu(c, &h->list, list, lockdep_is_held(&hdev->lock))
Although there should not be any remaining callsites without locks,
don't remove the rcu_read_lock() for now, and just add the warning here.

Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/hci_core.h | 44 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

(limited to 'include')

diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 4105c446ca98..c12cd6873f65 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1030,6 +1030,9 @@ static inline bool hci_conn_sc_enabled(struct hci_conn *conn)
 static inline void hci_conn_hash_add(struct hci_dev *hdev, struct hci_conn *c)
 {
 	struct hci_conn_hash *h = &hdev->conn_hash;
+
+	lockdep_assert_held(&hdev->lock);
+
 	list_add_tail_rcu(&c->list, &h->list);
 	switch (c->type) {
 	case ACL_LINK:
@@ -1060,6 +1063,8 @@ static inline void hci_conn_hash_del(struct hci_dev *hdev, struct hci_conn *c)
 {
 	struct hci_conn_hash *h = &hdev->conn_hash;
 
+	lockdep_assert_held(&hdev->lock);
+
 	list_del_rcu(&c->list);
 	synchronize_rcu();
 
@@ -1088,6 +1093,15 @@ static inline void hci_conn_hash_del(struct hci_dev *hdev, struct hci_conn *c)
 	}
 }
 
+#ifdef CONFIG_PROVE_RCU
+#define HCI_CONN_HASH_LOCKDEP_CHECK(hdev)				\
+	RCU_LOCKDEP_WARN(!lockdep_is_held(&(hdev)->lock) &&		\
+			 !rcu_read_lock_held(),				\
+			 "suspicious hci_conn locking")
+#else
+#define HCI_CONN_HASH_LOCKDEP_CHECK(hdev) do { } while (0 && (hdev))
+#endif
+
 static inline unsigned int hci_conn_num(struct hci_dev *hdev, __u8 type)
 {
 	struct hci_conn_hash *h = &hdev->conn_hash;
@@ -1169,6 +1183,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_bis(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1191,6 +1207,8 @@ hci_conn_hash_lookup_create_pa_sync(struct hci_dev *hdev)
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1217,6 +1235,8 @@ hci_conn_hash_lookup_per_adv_bis(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1241,6 +1261,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_handle(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1260,6 +1282,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_ba(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1281,6 +1305,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_role(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1302,6 +1328,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_le(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1328,6 +1356,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_cis(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1360,6 +1390,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_cig(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1383,6 +1415,8 @@ static inline struct hci_conn *hci_conn_hash_lookup_big(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1407,6 +1441,8 @@ hci_conn_hash_lookup_big_sync_pend(struct hci_dev *hdev,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1431,6 +1467,8 @@ hci_conn_hash_lookup_big_state(struct hci_dev *hdev, __u8 handle, __u16 state,
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1454,6 +1492,8 @@ hci_conn_hash_lookup_pa_sync_big_handle(struct hci_dev *hdev, __u8 big)
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1477,6 +1517,8 @@ hci_conn_hash_lookup_pa_sync_handle(struct hci_dev *hdev, __u16 sync_handle)
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
@@ -1546,6 +1588,8 @@ static inline struct hci_conn *hci_lookup_le_connect(struct hci_dev *hdev)
 	struct hci_conn_hash *h = &hdev->conn_hash;
 	struct hci_conn  *c;
 
+	HCI_CONN_HASH_LOCKDEP_CHECK(hdev);
+
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(c, &h->list, list) {
-- 
cgit v1.2.3


From a3dd57c495646a7b56f7b9e64f37a6d9b27e5254 Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sun, 16 Aug 2026 12:47:04 +0300
Subject: Bluetooth: L2CAP: add locking annotations for l2cap_chan_lock/unlock

Add minimal context analysis annotations to l2cap_chan_lock/unlock() and
callers required for no warnings.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h | 2 ++
 net/bluetooth/l2cap_core.c    | 1 +
 net/bluetooth/l2cap_sock.c    | 1 +
 3 files changed, 4 insertions(+)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 3d9a32094347..69d193fee351 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -830,11 +830,13 @@ struct l2cap_chan *l2cap_chan_hold_unless_zero(struct l2cap_chan *c);
 void l2cap_chan_put(struct l2cap_chan *c);
 
 static inline void l2cap_chan_lock(struct l2cap_chan *chan)
+	__acquires(&chan->lock)
 {
 	mutex_lock_nested(&chan->lock, atomic_read(&chan->nesting));
 }
 
 static inline void l2cap_chan_unlock(struct l2cap_chan *chan)
+	__releases(&chan->lock)
 {
 	mutex_unlock(&chan->lock);
 }
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index df41ef952500..358b11eabd4f 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4082,6 +4082,7 @@ static struct l2cap_chan *l2cap_new_connection(struct l2cap_conn *conn,
 
 static void l2cap_connect(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd,
 			  u8 *data, u8 rsp_code)
+	__context_unsafe(/* conditional locking */)
 {
 	struct l2cap_conn_req *req = (struct l2cap_conn_req *) data;
 	struct l2cap_conn_rsp rsp;
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 1194c37e466f..b553b6356af8 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -1784,6 +1784,7 @@ static void l2cap_sock_state_change_cb(struct l2cap_chan *chan, int state,
 static struct sk_buff *l2cap_sock_alloc_skb_cb(struct l2cap_chan *chan,
 					       unsigned long hdr_len,
 					       unsigned long len, int nb)
+	__must_hold(&chan->lock)
 {
 	struct sock *sk = chan->data;
 	struct sk_buff *skb;
-- 
cgit v1.2.3


From ca52f4764c8754d006e53cd7be3f2cb1a2b98fa4 Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sat, 29 Aug 2026 17:19:56 +0300
Subject: Bluetooth: L2CAP: take chan->lock for l2cap_chan_add/ready/del

chan->lock must be held for __l2cap_chan_add as eg. calls to
l2cap_chan_close assume chan->conn writes are guarded by it.

It must be held for l2cap_chan_del() due to
l2cap_sock.c:l2cap_chan_conn, l2cap_monitor_timeout, etc.

Similarly it should be held for l2cap_ops::ready (assumed in 6lowpan.c).
Also teardown usually has chan->lock held, it should always have it held
to have the same locking context.

The lock is not correctly held by l2cap_core in several places.

Add the missing locks for l2cap_chan_del/add/ready(), except in
l2cap_ecred_rsp_defer() which needs separate fix as it needs lock
nesting.

Fixes: 6fef032af009 ("Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connection_cb()")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Reported-by: Eulgyu Kim <eulgyukim@snu.ac.kr>
Reported-by: Jaeyoung Chung <jjy600901@snu.ac.kr>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h |  3 ++-
 net/bluetooth/l2cap_core.c    | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 69d193fee351..43a67562b238 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -973,7 +973,8 @@ int l2cap_chan_check_security(struct l2cap_chan *chan, bool initiator);
 void l2cap_chan_set_defaults(struct l2cap_chan *chan, struct l2cap_chan *pchan);
 int l2cap_ertm_init(struct l2cap_chan *chan);
 void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan);
-void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan);
+void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
+	__must_hold(&chan->lock);
 typedef void (*l2cap_chan_func_t)(struct l2cap_chan *chan, void *data);
 void l2cap_chan_list(struct l2cap_conn *conn, l2cap_chan_func_t func,
 		     void *data);
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 2410e8f6d587..e1430c183a8e 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -665,7 +665,9 @@ void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
 void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
 {
 	mutex_lock(&conn->lock);
+	l2cap_chan_lock(chan);
 	__l2cap_chan_add(conn, chan);
+	l2cap_chan_unlock(chan);
 	mutex_unlock(&conn->lock);
 }
 
@@ -4079,6 +4081,8 @@ static struct l2cap_chan *l2cap_new_connection(struct l2cap_conn *conn,
 	if (!chan)
 		return NULL;
 
+	l2cap_chan_lock(chan);
+
 	l2cap_chan_set_defaults(chan, pchan);
 	chan->ops = pchan->ops;
 
@@ -4087,10 +4091,13 @@ static struct l2cap_chan *l2cap_new_connection(struct l2cap_conn *conn,
 	if (pchan->ops->new_connection &&
 	    pchan->ops->new_connection(pchan, chan) < 0) {
 		l2cap_chan_del(chan, 0);
+		l2cap_chan_unlock(chan);
 		l2cap_chan_put(chan);
 		return NULL;
 	}
 
+	l2cap_chan_unlock(chan);
+
 	return chan;
 }
 
@@ -5061,6 +5068,8 @@ static int l2cap_le_connect_req(struct l2cap_conn *conn,
 		goto response_unlock;
 	}
 
+	l2cap_chan_lock(chan);
+
 	bacpy(&chan->src, &conn->hcon->src);
 	bacpy(&chan->dst, &conn->hcon->dst);
 	chan->src_type = bdaddr_src_type(conn->hcon);
@@ -5094,6 +5103,8 @@ static int l2cap_le_connect_req(struct l2cap_conn *conn,
 		result = L2CAP_CR_LE_SUCCESS;
 	}
 
+	l2cap_chan_unlock(chan);
+
 response_unlock:
 	l2cap_chan_unlock(pchan);
 	l2cap_chan_put(pchan);
@@ -5286,6 +5297,8 @@ static inline int l2cap_ecred_conn_req(struct l2cap_conn *conn,
 			continue;
 		}
 
+		l2cap_chan_lock(chan);
+
 		bacpy(&chan->src, &conn->hcon->src);
 		bacpy(&chan->dst, &conn->hcon->dst);
 		chan->src_type = bdaddr_src_type(conn->hcon);
@@ -5318,6 +5331,8 @@ static inline int l2cap_ecred_conn_req(struct l2cap_conn *conn,
 		} else {
 			l2cap_chan_ready(chan);
 		}
+
+		l2cap_chan_unlock(chan);
 	}
 
 unlock:
-- 
cgit v1.2.3


From 368dc7fcaced7635f5c444240e24bd882963e8ad Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sat, 29 Aug 2026 17:19:57 +0300
Subject: Bluetooth: L2CAP: add l2cap_chan_close_unlocked() and locking helpers

l2cap_chan_close() requires holding chan->lock and chan->conn->lock if
associated chan->conn exists, to guard eg. conn->chan_l. Taking the
locks with right ordering requires handling a race condition.

Add helper function l2cap_chan_(un)lock_conn that do the locking right.

Add l2cap_chan_close_unlocked() that does not require locks to be held,
as all callsites do this lock -> close -> unlock pattern.

Link: https://syzkaller.appspot.com/bug?extid=0e4ebcc970728e056324
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h | 17 ++++++++++++
 net/bluetooth/l2cap_core.c    | 61 +++++++++++++++++++++++++++++++++++++++----
 2 files changed, 73 insertions(+), 5 deletions(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 43a67562b238..84f557d354ca 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -962,6 +962,8 @@ int l2cap_add_scid(struct l2cap_chan *chan,  __u16 scid);
 
 struct l2cap_chan *l2cap_chan_create(void);
 void l2cap_chan_close(struct l2cap_chan *chan, int reason);
+void l2cap_chan_close_unlocked(struct l2cap_chan *chan, int reason)
+	__must_not_hold(&chan->lock);
 int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid,
 		       bdaddr_t *dst, u8 dst_type, u16 timeout);
 int l2cap_chan_reconfigure(struct l2cap_chan *chan, __u16 mtu);
@@ -988,4 +990,19 @@ void l2cap_conn_put(struct l2cap_conn *conn);
 int l2cap_register_user(struct l2cap_conn *conn, struct l2cap_user *user);
 void l2cap_unregister_user(struct l2cap_conn *conn, struct l2cap_user *user);
 
+bool l2cap_chan_lock_conn(struct l2cap_chan *chan)
+	__acquires(&chan->lock) __cond_acquires(true, &chan->conn->lock);
+
+/* Release macro for l2cap_chan_lock_conn, so context analysis understands it */
+#define l2cap_chan_unlock_conn(chan, conn_locked)			\
+	({								\
+		struct l2cap_chan *__chan = (chan);			\
+		struct l2cap_conn *__conn = __chan->conn;		\
+		l2cap_chan_unlock(__chan);				\
+		if (conn_locked) {					\
+			mutex_unlock(&__conn->lock);			\
+			l2cap_conn_put(__conn);				\
+		}							\
+	})
+
 #endif /* __L2CAP_H */
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index e1430c183a8e..3bf877be081d 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -59,6 +59,7 @@ static void l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
 static void l2cap_retrans_timeout(struct work_struct *work);
 static void l2cap_monitor_timeout(struct work_struct *work);
 static void l2cap_ack_timeout(struct work_struct *work);
+static void __l2cap_chan_close(struct l2cap_chan *chan, int reason);
 
 static inline u8 bdaddr_type(u8 link_type, u8 bdaddr_type)
 {
@@ -422,7 +423,7 @@ static void l2cap_chan_timeout(struct work_struct *work)
 	else
 		reason = ETIMEDOUT;
 
-	l2cap_chan_close(chan, reason);
+	__l2cap_chan_close(chan, reason);
 
 	chan->ops->close(chan);
 
@@ -829,7 +830,7 @@ static void l2cap_chan_connect_reject(struct l2cap_chan *chan)
 	l2cap_send_cmd(conn, chan->ident, L2CAP_CONN_RSP, sizeof(rsp), &rsp);
 }
 
-void l2cap_chan_close(struct l2cap_chan *chan, int reason)
+static void __l2cap_chan_close(struct l2cap_chan *chan, int reason)
 {
 	struct l2cap_conn *conn = chan->conn;
 
@@ -878,8 +879,58 @@ void l2cap_chan_close(struct l2cap_chan *chan, int reason)
 		break;
 	}
 }
+
+void l2cap_chan_close(struct l2cap_chan *chan, int reason)
+{
+	__l2cap_chan_close(chan, reason);
+}
 EXPORT_SYMBOL(l2cap_chan_close);
 
+/* Take chan->lock. If chan->conn is non-NULL, take new reference on it, take
+ * chan->conn->lock, and return true. Otherwise return false.
+ */
+bool l2cap_chan_lock_conn(struct l2cap_chan *chan)
+	__context_unsafe(/* conditional locking */)
+{
+	/* Handle conn->lock > chan->lock ordering + race on chan->conn */
+	for (;;) {
+		struct l2cap_conn *conn;
+
+		l2cap_chan_lock(chan);
+		conn = chan->conn;
+		if (conn)
+			l2cap_conn_get(conn);
+		l2cap_chan_unlock(chan);
+
+		if (conn)
+			mutex_lock(&conn->lock);
+
+		l2cap_chan_lock(chan);
+
+		if (chan->conn != conn) {
+			l2cap_chan_unlock(chan);
+			if (conn) {
+				mutex_unlock(&conn->lock);
+				l2cap_conn_put(conn);
+			}
+			schedule();
+			continue;
+		}
+
+		return chan->conn;
+	}
+}
+
+void l2cap_chan_close_unlocked(struct l2cap_chan *chan, int reason)
+{
+	bool have_conn;
+
+	have_conn = l2cap_chan_lock_conn(chan);
+	__l2cap_chan_close(chan, reason);
+	l2cap_chan_unlock_conn(chan, have_conn);
+}
+EXPORT_SYMBOL(l2cap_chan_close_unlocked);
+
 static inline u8 l2cap_get_auth_type(struct l2cap_chan *chan)
 {
 	switch (chan->chan_type) {
@@ -1570,7 +1621,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
 			if (!l2cap_mode_supported(chan->mode, conn->feat_mask)
 			    && test_bit(CONF_STATE2_DEVICE,
 					&chan->conf_state)) {
-				l2cap_chan_close(chan, ECONNRESET);
+				__l2cap_chan_close(chan, ECONNRESET);
 				l2cap_chan_unlock(chan);
 				continue;
 			}
@@ -1578,7 +1629,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
 			if (l2cap_check_enc_key_size(conn->hcon, chan))
 				l2cap_start_connection(chan);
 			else
-				l2cap_chan_close(chan, ECONNREFUSED);
+				__l2cap_chan_close(chan, ECONNREFUSED);
 
 		} else if (chan->state == BT_CONNECT2) {
 			struct l2cap_conn_rsp rsp;
@@ -7667,7 +7718,7 @@ static inline void l2cap_check_encryption(struct l2cap_chan *chan, u8 encrypt)
 			__set_chan_timer(chan, L2CAP_ENC_TIMEOUT);
 		} else if (chan->sec_level == BT_SECURITY_HIGH ||
 			   chan->sec_level == BT_SECURITY_FIPS)
-			l2cap_chan_close(chan, ECONNREFUSED);
+			__l2cap_chan_close(chan, ECONNREFUSED);
 	} else {
 		if (chan->sec_level == BT_SECURITY_MEDIUM)
 			__clear_chan_timer(chan);
-- 
cgit v1.2.3


From c5123fddfef12f97a2a897fee339130944c95b38 Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sat, 29 Aug 2026 17:20:00 +0300
Subject: Bluetooth: L2CAP: remove unused l2cap_chan_close()

l2cap_chan_close() is now unused, and l2cap_chan_close_unlocked() should
be used instead.

Remove l2cap_chan_close().

Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h | 1 -
 net/bluetooth/l2cap_core.c    | 6 ------
 2 files changed, 7 deletions(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 84f557d354ca..e395ab5493f7 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -961,7 +961,6 @@ int l2cap_add_psm(struct l2cap_chan *chan, bdaddr_t *src, __le16 psm);
 int l2cap_add_scid(struct l2cap_chan *chan,  __u16 scid);
 
 struct l2cap_chan *l2cap_chan_create(void);
-void l2cap_chan_close(struct l2cap_chan *chan, int reason);
 void l2cap_chan_close_unlocked(struct l2cap_chan *chan, int reason)
 	__must_not_hold(&chan->lock);
 int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid,
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 3bf877be081d..348803067c38 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -880,12 +880,6 @@ static void __l2cap_chan_close(struct l2cap_chan *chan, int reason)
 	}
 }
 
-void l2cap_chan_close(struct l2cap_chan *chan, int reason)
-{
-	__l2cap_chan_close(chan, reason);
-}
-EXPORT_SYMBOL(l2cap_chan_close);
-
 /* Take chan->lock. If chan->conn is non-NULL, take new reference on it, take
  * chan->conn->lock, and return true. Otherwise return false.
  */
-- 
cgit v1.2.3


From 886931f0c7e6fb6b3f596fe2397eb3a309da2755 Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sat, 29 Aug 2026 17:20:04 +0300
Subject: Bluetooth: L2CAP: add annotations for l2cap_chan list locking

Add context analysis annotations for l2cap_conn::chan_l and chan_list
locking.

Add corresponding required annotations to accessors and callers.

This is not complete chan_l annotation, l2cap_chan::list and
l2cap_chan_del() locking is currently not fully correct, and needs
separate fix + annotations.

Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h |  7 ++---
 net/bluetooth/l2cap_core.c    | 61 ++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 61 insertions(+), 7 deletions(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index e395ab5493f7..a991fc07515c 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -668,7 +668,7 @@ struct l2cap_conn {
 
 	struct l2cap_chan	*smp;
 
-	struct list_head	chan_l;
+	struct list_head	chan_l __guarded_by(&lock);
 	struct mutex		lock;
 	struct kref		ref;
 	struct list_head	users;
@@ -954,7 +954,8 @@ void l2cap_cleanup_sockets(void);
 bool l2cap_is_socket(struct socket *sock);
 
 void __l2cap_le_connect_rsp_defer(struct l2cap_chan *chan);
-void __l2cap_ecred_conn_rsp_defer(struct l2cap_chan *chan);
+void __l2cap_ecred_conn_rsp_defer(struct l2cap_chan *chan)
+	__must_hold(&chan->lock) __must_hold(&chan->conn->lock);
 void __l2cap_connect_rsp_defer(struct l2cap_chan *chan);
 
 int l2cap_add_psm(struct l2cap_chan *chan, bdaddr_t *src, __le16 psm);
@@ -975,7 +976,7 @@ void l2cap_chan_set_defaults(struct l2cap_chan *chan, struct l2cap_chan *pchan);
 int l2cap_ertm_init(struct l2cap_chan *chan);
 void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan);
 void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
-	__must_hold(&chan->lock);
+	__must_hold(&conn->lock) __must_hold(&chan->lock);
 typedef void (*l2cap_chan_func_t)(struct l2cap_chan *chan, void *data);
 void l2cap_chan_list(struct l2cap_conn *conn, l2cap_chan_func_t func,
 		     void *data);
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 116f809ab757..5af7da8d171f 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -44,8 +44,8 @@ bool enable_ecred = IS_ENABLED(CONFIG_BT_LE_L2CAP_ECRED);
 
 static u32 l2cap_feat_mask = L2CAP_FEAT_FIXED_CHAN | L2CAP_FEAT_UCD;
 
-static LIST_HEAD(chan_list);
 static DEFINE_RWLOCK(chan_list_lock);
+static __guarded_by(&chan_list_lock) LIST_HEAD(chan_list);
 
 static struct sk_buff *l2cap_build_cmd(struct l2cap_conn *conn,
 				       u8 code, u8 ident, u16 dlen, void *data);
@@ -87,6 +87,7 @@ static inline u8 bdaddr_dst_type(struct hci_conn *hcon)
 
 static struct l2cap_chan *__l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 						   u16 cid)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *c;
 
@@ -99,6 +100,7 @@ static struct l2cap_chan *__l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 
 static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn,
 						   u16 cid)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *c;
 
@@ -114,6 +116,7 @@ static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn,
  */
 static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn,
 						 u16 cid)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *c;
 
@@ -129,6 +132,7 @@ static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn,
  */
 static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 						 u16 cid)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *c;
 
@@ -141,6 +145,7 @@ static struct l2cap_chan *l2cap_get_chan_by_dcid(struct l2cap_conn *conn,
 
 static struct l2cap_chan *__l2cap_get_chan_by_ident(struct l2cap_conn *conn,
 						    u8 ident)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *c;
 
@@ -153,6 +158,7 @@ static struct l2cap_chan *__l2cap_get_chan_by_ident(struct l2cap_conn *conn,
 
 static struct l2cap_chan *__l2cap_global_chan_by_addr(__le16 psm, bdaddr_t *src,
 						      u8 src_type)
+	__must_hold_shared(&chan_list_lock)
 {
 	struct l2cap_chan *c;
 
@@ -230,6 +236,7 @@ int l2cap_add_scid(struct l2cap_chan *chan,  __u16 scid)
 }
 
 static u16 l2cap_alloc_cid(struct l2cap_conn *conn)
+	__must_hold(&conn->lock)
 {
 	u16 cid, dyn_end;
 
@@ -728,6 +735,7 @@ EXPORT_SYMBOL_GPL(l2cap_chan_del);
 
 static void __l2cap_chan_list_id(struct l2cap_conn *conn, u16 id,
 				 l2cap_chan_func_t func, void *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *chan, *l;
 
@@ -739,6 +747,7 @@ static void __l2cap_chan_list_id(struct l2cap_conn *conn, u16 id,
 
 static void __l2cap_chan_list(struct l2cap_conn *conn, l2cap_chan_func_t func,
 			      void *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *chan;
 
@@ -806,6 +815,9 @@ static void l2cap_chan_ecred_connect_reject(struct l2cap_chan *chan)
 {
 	l2cap_state_change(chan, BT_DISCONN);
 
+	lockdep_assert_held(&chan->lock);
+	lockdep_assert_held(&chan->conn->lock);
+
 	__l2cap_ecred_conn_rsp_defer(chan);
 }
 
@@ -1423,6 +1435,7 @@ static void l2cap_ecred_defer_connect(struct l2cap_chan *chan, void *data)
 }
 
 static void l2cap_ecred_connect(struct l2cap_chan *chan)
+	__must_hold(&chan->conn->lock)
 {
 	struct l2cap_conn *conn = chan->conn;
 	struct l2cap_ecred_conn_data data;
@@ -1456,6 +1469,7 @@ static void l2cap_ecred_connect(struct l2cap_chan *chan)
 }
 
 static void l2cap_le_start(struct l2cap_chan *chan)
+	__must_hold(&chan->conn->lock)
 {
 	struct l2cap_conn *conn = chan->conn;
 
@@ -1476,6 +1490,7 @@ static void l2cap_le_start(struct l2cap_chan *chan)
 }
 
 static void l2cap_start_connection(struct l2cap_chan *chan)
+	__must_hold(&chan->conn->lock)
 {
 	if (chan->conn->hcon->type == LE_LINK) {
 		l2cap_le_start(chan);
@@ -1525,6 +1540,7 @@ static bool l2cap_check_enc_key_size(struct hci_conn *hcon,
 }
 
 static void l2cap_do_start(struct l2cap_chan *chan)
+	__must_hold(&chan->conn->lock)
 {
 	struct l2cap_conn *conn = chan->conn;
 
@@ -1591,6 +1607,7 @@ static void l2cap_send_disconn_req(struct l2cap_chan *chan, int err)
 
 /* ---- L2CAP connections ---- */
 static void l2cap_conn_start(struct l2cap_conn *conn)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *chan, *tmp;
 
@@ -1599,6 +1616,8 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
 	list_for_each_entry_safe(chan, tmp, &conn->chan_l, list) {
 		l2cap_chan_lock(chan);
 
+		lockdep_assert_held(&chan->conn->lock);
+
 		if (chan->chan_type != L2CAP_CHAN_CONN_ORIENTED) {
 			l2cap_chan_ready(chan);
 			l2cap_chan_unlock(chan);
@@ -1715,6 +1734,8 @@ static void l2cap_conn_ready(struct l2cap_conn *conn)
 
 		l2cap_chan_lock(chan);
 
+		lockdep_assert_held(&chan->conn->lock);
+
 		if (hcon->type == LE_LINK) {
 			l2cap_le_start(chan);
 		} else if (chan->chan_type != L2CAP_CHAN_CONN_ORIENTED) {
@@ -1737,6 +1758,7 @@ static void l2cap_conn_ready(struct l2cap_conn *conn)
 
 /* Notify sockets that we cannot guaranty reliability anymore */
 static void l2cap_conn_unreliable(struct l2cap_conn *conn, int err)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *chan;
 
@@ -3034,6 +3056,7 @@ static void l2cap_pass_to_tx_fbit(struct l2cap_chan *chan,
 
 /* Copy frame to all raw sockets on that connection */
 static void l2cap_raw_recv(struct l2cap_conn *conn, struct sk_buff *skb)
+	__must_hold(&conn->lock)
 {
 	struct sk_buff *nskb;
 	struct l2cap_chan *chan;
@@ -4087,6 +4110,7 @@ static void l2cap_conf_rfc_get(struct l2cap_chan *chan, void *rsp, int len)
 static inline int l2cap_command_rej(struct l2cap_conn *conn,
 				    struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				    u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_cmd_rej_unk *rej = (struct l2cap_cmd_rej_unk *) data;
 
@@ -4119,6 +4143,7 @@ static inline int l2cap_command_rej(struct l2cap_conn *conn,
  */
 static struct l2cap_chan *l2cap_new_connection(struct l2cap_conn *conn,
 					       struct l2cap_chan *pchan)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *chan;
 
@@ -4148,6 +4173,7 @@ static struct l2cap_chan *l2cap_new_connection(struct l2cap_conn *conn,
 
 static void l2cap_connect(struct l2cap_conn *conn, struct l2cap_cmd_hdr *cmd,
 			  u8 *data, u8 rsp_code)
+	__must_hold(&conn->lock)
 	__context_unsafe(/* conditional locking */)
 {
 	struct l2cap_conn_req *req = (struct l2cap_conn_req *) data;
@@ -4278,6 +4304,7 @@ response:
 
 static int l2cap_connect_req(struct l2cap_conn *conn,
 			     struct l2cap_cmd_hdr *cmd, u16 cmd_len, u8 *data)
+	__must_hold(&conn->lock)
 {
 	if (cmd_len < sizeof(struct l2cap_conn_req))
 		return -EPROTO;
@@ -4289,6 +4316,7 @@ static int l2cap_connect_req(struct l2cap_conn *conn,
 static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 				    struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				    u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_conn_rsp *rsp = (struct l2cap_conn_rsp *) data;
 	u16 scid, dcid, result, status;
@@ -4406,6 +4434,7 @@ static void cmd_reject_invalid_cid(struct l2cap_conn *conn, u8 ident,
 static inline int l2cap_config_req(struct l2cap_conn *conn,
 				   struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				   u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_conf_req *req = (struct l2cap_conf_req *) data;
 	u16 dcid, flags;
@@ -4519,6 +4548,7 @@ unlock:
 static inline int l2cap_config_rsp(struct l2cap_conn *conn,
 				   struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				   u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_conf_rsp *rsp = (struct l2cap_conf_rsp *)data;
 	u16 scid, flags, result;
@@ -4628,6 +4658,7 @@ done:
 static inline int l2cap_disconnect_req(struct l2cap_conn *conn,
 				       struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				       u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_disconn_req *req = (struct l2cap_disconn_req *) data;
 	struct l2cap_disconn_rsp rsp;
@@ -4669,6 +4700,7 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn,
 static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn,
 				       struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				       u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_disconn_rsp *rsp = (struct l2cap_disconn_rsp *) data;
 	u16 dcid, scid;
@@ -4756,6 +4788,7 @@ static inline int l2cap_information_req(struct l2cap_conn *conn,
 static inline int l2cap_information_rsp(struct l2cap_conn *conn,
 					struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 					u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_info_rsp *rsp = (struct l2cap_info_rsp *) data;
 	u16 type, result;
@@ -4863,6 +4896,7 @@ static inline int l2cap_conn_param_update_req(struct l2cap_conn *conn,
 static int l2cap_le_connect_rsp(struct l2cap_conn *conn,
 				struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_le_conn_rsp *rsp = (struct l2cap_le_conn_rsp *) data;
 	struct hci_conn *hcon = conn->hcon;
@@ -4969,6 +5003,7 @@ static void l2cap_put_ident(struct l2cap_conn *conn, u8 code, u8 id)
 static inline int l2cap_bredr_sig_cmd(struct l2cap_conn *conn,
 				      struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				      u8 *data)
+	__must_hold(&conn->lock)
 {
 	int err = 0;
 
@@ -5030,6 +5065,7 @@ static inline int l2cap_bredr_sig_cmd(struct l2cap_conn *conn,
 static int l2cap_le_connect_req(struct l2cap_conn *conn,
 				struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_le_conn_req *req = (struct l2cap_le_conn_req *) data;
 	struct l2cap_le_conn_rsp rsp;
@@ -5178,6 +5214,7 @@ response:
 static inline int l2cap_le_credits(struct l2cap_conn *conn,
 				   struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				   u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_le_credits *pkt;
 	struct l2cap_chan *chan;
@@ -5227,6 +5264,7 @@ unlock:
 static inline int l2cap_ecred_conn_req(struct l2cap_conn *conn,
 				       struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				       u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_ecred_conn_req *req = (void *) data;
 	DEFINE_RAW_FLEX(struct l2cap_ecred_conn_rsp, pdu, dcid, L2CAP_ECRED_MAX_CID);
@@ -5399,6 +5437,7 @@ response:
 static inline int l2cap_ecred_conn_rsp(struct l2cap_conn *conn,
 				       struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				       u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_ecred_conn_rsp *rsp = (void *) data;
 	struct hci_conn *hcon = conn->hcon;
@@ -5526,6 +5565,7 @@ static inline int l2cap_ecred_conn_rsp(struct l2cap_conn *conn,
 static inline int l2cap_ecred_reconf_req(struct l2cap_conn *conn,
 					 struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 					 u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_ecred_reconf_req *req = (void *) data;
 	struct l2cap_ecred_reconf_rsp rsp;
@@ -5624,6 +5664,7 @@ respond:
 static inline int l2cap_ecred_reconf_rsp(struct l2cap_conn *conn,
 					 struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 					 u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *chan, *tmp;
 	struct l2cap_ecred_reconf_rsp *rsp = (void *)data;
@@ -5664,6 +5705,7 @@ static inline int l2cap_ecred_reconf_rsp(struct l2cap_conn *conn,
 static inline int l2cap_le_command_rej(struct l2cap_conn *conn,
 				       struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				       u8 *data)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_cmd_rej_unk *rej = (struct l2cap_cmd_rej_unk *) data;
 	struct l2cap_chan *chan;
@@ -5691,6 +5733,7 @@ done:
 static inline int l2cap_le_sig_cmd(struct l2cap_conn *conn,
 				   struct l2cap_cmd_hdr *cmd, u16 cmd_len,
 				   u8 *data)
+	__must_hold(&conn->lock)
 {
 	int err = 0;
 
@@ -5755,6 +5798,7 @@ static inline int l2cap_le_sig_cmd(struct l2cap_conn *conn,
 
 static inline void l2cap_le_sig_channel(struct l2cap_conn *conn,
 					struct sk_buff *skb)
+	__must_hold(&conn->lock)
 {
 	struct hci_conn *hcon = conn->hcon;
 	struct l2cap_cmd_hdr *cmd;
@@ -5813,6 +5857,7 @@ static inline void l2cap_sig_send_mtu_rej(struct l2cap_conn *conn, u8 ident)
 
 static inline void l2cap_sig_channel(struct l2cap_conn *conn,
 				     struct sk_buff *skb)
+	__must_hold(&conn->lock)
 {
 	struct hci_conn *hcon = conn->hcon;
 	struct l2cap_cmd_hdr *cmd;
@@ -7050,6 +7095,7 @@ failed:
 
 static void l2cap_data_channel(struct l2cap_conn *conn, u16 cid,
 			       struct sk_buff *skb)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_chan *chan;
 
@@ -7158,6 +7204,7 @@ free_skb:
 }
 
 static void l2cap_recv_frame(struct l2cap_conn *conn, struct sk_buff *skb)
+	__must_hold(&conn->lock)
 {
 	struct l2cap_hdr *lh = (void *) skb->data;
 	struct hci_conn *hcon = conn->hcon;
@@ -7267,9 +7314,9 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon)
 	     hci_dev_test_flag(hcon->hdev, HCI_FORCE_BREDR_SMP)))
 		conn->local_fixed_chan |= L2CAP_FC_SMP_BREDR;
 
-	mutex_init(&conn->lock);
-
-	INIT_LIST_HEAD(&conn->chan_l);
+	scoped_guard(mutex_init, &conn->lock) {
+		INIT_LIST_HEAD(&conn->chan_l);
+	}
 	INIT_LIST_HEAD(&conn->users);
 
 	INIT_DELAYED_WORK(&conn->info_timer, l2cap_info_timeout);
@@ -7485,6 +7532,8 @@ int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid,
 
 	__l2cap_chan_add(conn, chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	/* l2cap_chan_add takes its own ref so we can drop this one */
 	hci_conn_drop(hcon);
 
@@ -7707,6 +7756,8 @@ static void l2cap_disconn_cfm(struct hci_conn *hcon, u8 reason)
 }
 
 static inline void l2cap_check_encryption(struct l2cap_chan *chan, u8 encrypt)
+	__must_hold(&chan->lock)
+	__must_hold(&chan->conn->lock)
 {
 	if (chan->chan_type != L2CAP_CHAN_CONN_ORIENTED)
 		return;
@@ -7739,6 +7790,8 @@ static void l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt)
 	list_for_each_entry(chan, &conn->chan_l, list) {
 		l2cap_chan_lock(chan);
 
+		lockdep_assert_held(&chan->conn->lock);
+
 		BT_DBG("chan %p scid 0x%4.4x state %s", chan, chan->scid,
 		       state_to_string(chan->state));
 
-- 
cgit v1.2.3


From 761224d13f8a5d84a9c06b9948a37b1b1dbc7837 Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Sat, 29 Aug 2026 17:20:09 +0300
Subject: Bluetooth: L2CAP: make concurrent l2cap_set_timer() refcounting safe

Since l2cap_set_timer() does not check return value of
schedule_delayed_work(), two concurrent calls may result to l2cap_chan
refcount leak.

Change the refcounting by using mod_delayed_work() and checking its
return value.

Code paths aside from l2cap_chan_busy() hold chan->lock, so this has
little correctness impact.

Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index a991fc07515c..2315a3993c7b 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -847,12 +847,11 @@ static inline void l2cap_set_timer(struct l2cap_chan *chan,
 	BT_DBG("chan %p state %s timeout %ld", chan,
 	       state_to_string(chan->state), timeout);
 
-	/* If delayed work cancelled do not hold(chan)
-	   since it is already done with previous set_timer */
-	if (!cancel_delayed_work(work))
-		l2cap_chan_hold(chan);
+	l2cap_chan_hold(chan);
 
-	schedule_delayed_work(work, timeout);
+	/* put(chan) if timer was already queued so it already has a ref */
+	if (mod_delayed_work(system_percpu_wq, work, timeout))
+		l2cap_chan_put(chan);
 }
 
 static inline bool l2cap_clear_timer(struct l2cap_chan *chan,
-- 
cgit v1.2.3


From c6d60c24cd7b3d74d1f7ad5db5651cb581801cc4 Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Wed, 2 Sep 2026 00:04:33 +0300
Subject: Bluetooth: L2CAP: take lock for l2cap_chan_del in
 l2cap_ecred_rsp_defer

l2cap_ecred_rsp_defer() calls l2cap_chan_del without holding chan->lock,
which ends up calling ops->teardown() with wrong lock context.

Fix by taking chan->lock in l2cap_ecred_rsp_defer().  AB-BA deadlocks
between sibling l2cap_chan are avoided here via requiring l2cap_conn::lock
to serialize all nested l2cap_chan locking on same nesting level.

In current code, there is no nested l2cap_chan locking on same nesting
level, so we can add this new requirement.

Also return early from  __l2cap_ecred_conn_rsp_defer() if chan did not
have FLAG_DEFER_SETUP, as then no RSP shall be sent for it, to make sure
SMP channels are excluded.

Also hold chan reference over l2cap_chan_del(), in case chan_l reference
was the last.

Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h |  4 +++
 net/bluetooth/l2cap_core.c    | 60 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 2315a3993c7b..c7e642abe404 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -758,6 +758,10 @@ enum {
  * otherwise considers all channels equal and will e.g. complain about a
  * connection oriented channel triggering SMP procedures or a listening
  * channel creating and locking a child channel.
+ *
+ * Lock nesting of channels at the same nesting level is allowed if the channels
+ * have the same l2cap_chan::conn and l2cap_chan::conn.lock is taken before the
+ * nested locks. l2cap_chan_try_sibling_lock() must be used.
  */
 enum {
 	L2CAP_NESTING_SMP,
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 9da689f0a50a..805623a48bae 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -848,6 +848,8 @@ static void __l2cap_chan_close(struct l2cap_chan *chan, int reason)
 
 	BT_DBG("chan %p state %s", chan, state_to_string(chan->state));
 
+	lockdep_assert_held(&chan->lock);
+
 	switch (chan->state) {
 	case BT_LISTEN:
 		chan->ops->teardown(chan, 0);
@@ -3950,6 +3952,7 @@ static void l2cap_ecred_list_defer(struct l2cap_chan *chan, void *data)
 }
 
 struct l2cap_ecred_rsp_data {
+	struct l2cap_chan *locked_chan;
 	struct {
 		struct l2cap_ecred_conn_rsp_hdr rsp;
 		__le16 scid[L2CAP_ECRED_MAX_CID];
@@ -3957,11 +3960,42 @@ struct l2cap_ecred_rsp_data {
 	int count;
 };
 
+/* Lock @chan if it is not @locked_chan, and has same or lower nesting level.
+ *
+ * They must have the same chan->conn, and conn->lock must be held.
+ *
+ * Caller must ensure @chan has lock nesting level <= that of @locked_chan, as
+ * nested locking of l2cap_chan of different levels is allowed also without
+ * holding conn->lock.
+ *
+ * See l2cap.h for the global l2cap_chan locking rules.
+ */
+static bool l2cap_chan_try_sibling_lock(struct l2cap_chan *chan,
+					struct l2cap_chan *locked_chan)
+	__must_hold(&locked_chan->lock)
+	__must_hold(&locked_chan->conn->lock)
+	__cond_acquires(true, &chan->lock)
+{
+	if (chan == locked_chan)
+		return false;
+
+	if (WARN_ON_ONCE(locked_chan->conn != chan->conn))
+		return false;
+
+	if (WARN_ON_ONCE(atomic_read(&locked_chan->nesting)
+			 < atomic_read(&chan->nesting)))
+		return false;
+
+	mutex_lock_nest_lock(&chan->lock, &locked_chan->conn->lock);
+	return true;
+}
+
 static void l2cap_ecred_rsp_defer(struct l2cap_chan *chan, void *data)
 {
 	struct l2cap_ecred_rsp_data *rsp = data;
 	struct l2cap_ecred_conn_rsp *rsp_flex =
 		container_of(&rsp->pdu.rsp, struct l2cap_ecred_conn_rsp, hdr);
+	bool locked;
 
 	if (chan->mode != L2CAP_MODE_EXT_FLOWCTL)
 		return;
@@ -3973,6 +4007,22 @@ static void l2cap_ecred_rsp_defer(struct l2cap_chan *chan, void *data)
 	    !test_and_clear_bit(FLAG_DEFER_SETUP, &chan->flags))
 		return;
 
+	lockdep_assert_held(&rsp->locked_chan->lock);
+	lockdep_assert_held(&rsp->locked_chan->conn->lock);
+
+	l2cap_chan_hold(chan);
+
+	locked = l2cap_chan_try_sibling_lock(chan, rsp->locked_chan);
+
+	/* Cannot occur: PARENT channels do not appear in chan_l, and SMP
+	 * channels never have FLAG_DEFER_SETUP.
+	 */
+	if (context_unsafe(!locked && chan != rsp->locked_chan))
+		goto done;
+
+	lockdep_assert_held(&chan->lock);
+	lockdep_assert_held(&chan->conn->lock);
+
 	/* Reset ident so only one response is sent */
 	chan->ident = 0;
 
@@ -3985,6 +4035,12 @@ static void l2cap_ecred_rsp_defer(struct l2cap_chan *chan, void *data)
 		rsp_flex->dcid[rsp->count++] = cpu_to_le16(chan->scid);
 	else
 		l2cap_chan_del(chan, ECONNRESET);
+
+done:
+	if (locked)
+		l2cap_chan_unlock(chan);
+
+	l2cap_chan_put(chan);
 }
 
 void __l2cap_ecred_conn_rsp_defer(struct l2cap_chan *chan)
@@ -3996,11 +4052,15 @@ void __l2cap_ecred_conn_rsp_defer(struct l2cap_chan *chan)
 
 	if (!id)
 		return;
+	if (!test_bit(FLAG_DEFER_SETUP, &chan->flags))
+		return;
 
 	BT_DBG("chan %p id %d", chan, id);
 
 	memset(&data, 0, sizeof(data));
 
+	data.locked_chan = chan;
+
 	data.pdu.rsp.mtu     = cpu_to_le16(chan->imtu);
 	data.pdu.rsp.mps     = cpu_to_le16(chan->mps);
 	data.pdu.rsp.credits = cpu_to_le16(chan->rx_credits);
-- 
cgit v1.2.3


From 6873eb51dcdd9ae01f8c682e482c8915dbbb138f Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Wed, 2 Sep 2026 00:04:34 +0300
Subject: Bluetooth: L2CAP: annotate locking for l2cap_chan_del()

Add context analysis annotations for chan->lock and chan->conn->lock
involving l2cap_chan_del() usage.

Add necessary annotations and related lockdep_assert_held to callers.

Move struct l2cap_ops definition after struct l2cap_conn, so that the
callbacks can be annotated.

In l2cap_chan_close_unlocked() we consider chan->conn->lock as locked
even if chan->conn == NULL, to avoid needing to define separate
__l2cap_chan_close/del for this NULL case.

Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h | 56 +++++++++++++++++++++++--------------------
 net/bluetooth/6lowpan.c       |  2 ++
 net/bluetooth/l2cap_core.c    | 49 +++++++++++++++++++++++++++++++------
 3 files changed, 74 insertions(+), 33 deletions(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index c7e642abe404..3e1e2b36d7b6 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -614,31 +614,6 @@ struct l2cap_chan {
 	struct mutex		lock;
 };
 
-struct l2cap_ops {
-	char			*name;
-
-	int			(*new_connection)(struct l2cap_chan *chan,
-						  struct l2cap_chan *new_chan);
-	int			(*recv) (struct l2cap_chan * chan,
-					 struct sk_buff *skb);
-	void			(*teardown) (struct l2cap_chan *chan, int err);
-	void			(*close) (struct l2cap_chan *chan);
-	void			(*state_change) (struct l2cap_chan *chan,
-						 int state, int err);
-	void			(*ready) (struct l2cap_chan *chan);
-	void			(*defer) (struct l2cap_chan *chan);
-	void			(*resume) (struct l2cap_chan *chan);
-	void			(*suspend) (struct l2cap_chan *chan);
-	void			(*set_shutdown) (struct l2cap_chan *chan);
-	long			(*get_sndtimeo) (struct l2cap_chan *chan);
-	struct pid		*(*get_peer_pid) (struct l2cap_chan *chan);
-	struct sk_buff		*(*alloc_skb) (struct l2cap_chan *chan,
-					       unsigned long hdr_len,
-					       unsigned long len, int nb);
-	int			(*filter) (struct l2cap_chan * chan,
-					   struct sk_buff *skb);
-};
-
 struct l2cap_conn {
 	struct hci_conn		*hcon;
 	struct hci_chan		*hchan;
@@ -674,6 +649,34 @@ struct l2cap_conn {
 	struct list_head	users;
 };
 
+struct l2cap_ops {
+	char			*name;
+
+	int			(*new_connection)(struct l2cap_chan *chan,
+						  struct l2cap_chan *new_chan);
+	int			(*recv) (struct l2cap_chan * chan,
+					 struct sk_buff *skb);
+	void			(*teardown) (struct l2cap_chan *chan, int err)
+					__must_hold(&chan->lock);
+	void			(*close) (struct l2cap_chan *chan);
+	void			(*state_change) (struct l2cap_chan *chan,
+						 int state, int err);
+	void			(*ready) (struct l2cap_chan *chan)
+					__must_hold(&chan->lock)
+					__must_hold(&chan->conn->lock);
+	void			(*defer) (struct l2cap_chan *chan);
+	void			(*resume) (struct l2cap_chan *chan);
+	void			(*suspend) (struct l2cap_chan *chan);
+	void			(*set_shutdown) (struct l2cap_chan *chan);
+	long			(*get_sndtimeo) (struct l2cap_chan *chan);
+	struct pid		*(*get_peer_pid) (struct l2cap_chan *chan);
+	struct sk_buff		*(*alloc_skb) (struct l2cap_chan *chan,
+					       unsigned long hdr_len,
+					       unsigned long len, int nb);
+	int			(*filter) (struct l2cap_chan * chan,
+					   struct sk_buff *skb);
+};
+
 struct l2cap_user {
 	struct list_head list;
 	int (*probe) (struct l2cap_conn *conn, struct l2cap_user *user);
@@ -983,7 +986,8 @@ void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
 typedef void (*l2cap_chan_func_t)(struct l2cap_chan *chan, void *data);
 void l2cap_chan_list(struct l2cap_conn *conn, l2cap_chan_func_t func,
 		     void *data);
-void l2cap_chan_del(struct l2cap_chan *chan, int err);
+void l2cap_chan_del(struct l2cap_chan *chan, int err)
+	__must_hold(&chan->lock) __must_hold(&chan->conn->lock);
 void l2cap_send_conn_req(struct l2cap_chan *chan);
 
 struct l2cap_conn *l2cap_conn_get(struct l2cap_conn *conn);
diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index ddcdd2aff91f..836add41f5d1 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -722,6 +722,8 @@ out:
 }
 
 static inline void chan_ready_cb(struct l2cap_chan *chan)
+	__must_hold(&chan->lock)
+	__must_hold(&chan->conn->lock)
 {
 	struct lowpan_btle_dev *dev;
 	bool new_netdev = false;
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 805623a48bae..219d92431be0 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -59,7 +59,8 @@ static void l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
 static void l2cap_retrans_timeout(struct work_struct *work);
 static void l2cap_monitor_timeout(struct work_struct *work);
 static void l2cap_ack_timeout(struct work_struct *work);
-static void __l2cap_chan_close(struct l2cap_chan *chan, int reason);
+static void __l2cap_chan_close(struct l2cap_chan *chan, int reason)
+	__must_hold(&chan->lock) __must_hold(&chan->conn->lock);
 
 static inline u8 bdaddr_type(u8 link_type, u8 bdaddr_type)
 {
@@ -681,6 +682,8 @@ void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
 
 void l2cap_chan_del(struct l2cap_chan *chan, int err)
 {
+	lockdep_assert(!chan->conn || lockdep_is_held(&chan->conn->lock));
+
 	__clear_chan_timer(chan);
 
 	BT_DBG("chan %p, err %d, state %s", chan, err,
@@ -812,12 +815,11 @@ static void l2cap_chan_le_connect_reject(struct l2cap_chan *chan)
 }
 
 static void l2cap_chan_ecred_connect_reject(struct l2cap_chan *chan)
+	__must_hold(&chan->lock)
+	__must_hold(&chan->conn->lock)
 {
 	l2cap_state_change(chan, BT_DISCONN);
 
-	lockdep_assert_held(&chan->lock);
-	lockdep_assert_held(&chan->conn->lock);
-
 	__l2cap_ecred_conn_rsp_defer(chan);
 }
 
@@ -848,8 +850,6 @@ static void __l2cap_chan_close(struct l2cap_chan *chan, int reason)
 
 	BT_DBG("chan %p state %s", chan, state_to_string(chan->state));
 
-	lockdep_assert_held(&chan->lock);
-
 	switch (chan->state) {
 	case BT_LISTEN:
 		chan->ops->teardown(chan, 0);
@@ -934,7 +934,10 @@ void l2cap_chan_close_unlocked(struct l2cap_chan *chan, int reason)
 	bool have_conn;
 
 	have_conn = l2cap_chan_lock_conn(chan);
-	__l2cap_chan_close(chan, reason);
+
+	/* Context analysis: consider chan->conn->lock held also if conn NULL */
+	context_unsafe(__l2cap_chan_close(chan, reason));
+
 	l2cap_chan_unlock_conn(chan, have_conn);
 }
 EXPORT_SYMBOL(l2cap_chan_close_unlocked);
@@ -1336,6 +1339,8 @@ void l2cap_send_conn_req(struct l2cap_chan *chan)
 }
 
 static void l2cap_chan_ready(struct l2cap_chan *chan)
+	__must_hold(&chan->lock)
+	__must_hold(&chan->conn->lock)
 {
 	/* The channel may have already been flagged as connected in
 	 * case of receiving data before the L2CAP info req/rsp
@@ -1471,6 +1476,7 @@ static void l2cap_ecred_connect(struct l2cap_chan *chan)
 }
 
 static void l2cap_le_start(struct l2cap_chan *chan)
+	__must_hold(&chan->lock)
 	__must_hold(&chan->conn->lock)
 {
 	struct l2cap_conn *conn = chan->conn;
@@ -1492,6 +1498,7 @@ static void l2cap_le_start(struct l2cap_chan *chan)
 }
 
 static void l2cap_start_connection(struct l2cap_chan *chan)
+	__must_hold(&chan->lock)
 	__must_hold(&chan->conn->lock)
 {
 	if (chan->conn->hcon->type == LE_LINK) {
@@ -1542,6 +1549,7 @@ static bool l2cap_check_enc_key_size(struct hci_conn *hcon,
 }
 
 static void l2cap_do_start(struct l2cap_chan *chan)
+	__must_hold(&chan->lock)
 	__must_hold(&chan->conn->lock)
 {
 	struct l2cap_conn *conn = chan->conn;
@@ -1893,6 +1901,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
 		l2cap_chan_hold(chan);
 		l2cap_chan_lock(chan);
 
+		lockdep_assert_held(&chan->conn->lock);
+
 		l2cap_chan_del(chan, err);
 
 		chan->ops->close(chan);
@@ -4218,6 +4228,8 @@ static struct l2cap_chan *l2cap_new_connection(struct l2cap_conn *conn,
 
 	__l2cap_chan_add(conn, chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	if (pchan->ops->new_connection &&
 	    pchan->ops->new_connection(pchan, chan) < 0) {
 		l2cap_chan_del(chan, 0);
@@ -4419,6 +4431,8 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	switch (result) {
 	case L2CAP_CR_SUCCESS:
 		if (__l2cap_get_chan_by_dcid(conn, dcid)) {
@@ -4520,6 +4534,8 @@ static inline int l2cap_config_req(struct l2cap_conn *conn,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	if (chan->state != BT_CONFIG && chan->state != BT_CONNECT2 &&
 	    chan->state != BT_CONNECTED) {
 		cmd_reject_invalid_cid(conn, cmd->ident, chan->scid,
@@ -4634,6 +4650,8 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	switch (result) {
 	case L2CAP_CONF_SUCCESS:
 		l2cap_conf_rfc_get(chan, rsp->data, len);
@@ -4743,6 +4761,8 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	rsp.dcid = cpu_to_le16(chan->scid);
 	rsp.scid = cpu_to_le16(chan->dcid);
 	l2cap_send_cmd(conn, cmd->ident, L2CAP_DISCONN_RSP, sizeof(rsp), &rsp);
@@ -4783,6 +4803,8 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	if (chan->state != BT_DISCONN) {
 		l2cap_chan_unlock(chan);
 		l2cap_chan_put(chan);
@@ -4995,6 +5017,8 @@ static int l2cap_le_connect_rsp(struct l2cap_conn *conn,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	switch (result) {
 	case L2CAP_CR_LE_SUCCESS:
 		if (__l2cap_get_chan_by_dcid(conn, dcid)) {
@@ -5213,6 +5237,8 @@ static int l2cap_le_connect_req(struct l2cap_conn *conn,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	bacpy(&chan->src, &conn->hcon->src);
 	bacpy(&chan->dst, &conn->hcon->dst);
 	chan->src_type = bdaddr_src_type(conn->hcon);
@@ -5444,6 +5470,8 @@ static inline int l2cap_ecred_conn_req(struct l2cap_conn *conn,
 
 		l2cap_chan_lock(chan);
 
+		lockdep_assert_held(&chan->conn->lock);
+
 		bacpy(&chan->src, &conn->hcon->src);
 		bacpy(&chan->dst, &conn->hcon->dst);
 		chan->src_type = bdaddr_src_type(conn->hcon);
@@ -5533,6 +5561,8 @@ static inline int l2cap_ecred_conn_rsp(struct l2cap_conn *conn,
 		l2cap_chan_hold(chan);
 		l2cap_chan_lock(chan);
 
+		lockdep_assert_held(&chan->conn->lock);
+
 		/* Check that there is a dcid for each pending channel */
 		if (cmd_len < sizeof(dcid)) {
 			l2cap_chan_del(chan, ECONNREFUSED);
@@ -5760,6 +5790,8 @@ static inline int l2cap_ecred_reconf_rsp(struct l2cap_conn *conn,
 			continue;
 		l2cap_chan_lock(chan);
 
+		lockdep_assert_held(&chan->conn->lock);
+
 		l2cap_chan_del(chan, ECONNRESET);
 
 		l2cap_chan_unlock(chan);
@@ -5789,6 +5821,7 @@ static inline int l2cap_le_command_rej(struct l2cap_conn *conn,
 		goto done;
 
 	l2cap_chan_lock(chan);
+	lockdep_assert_held(&chan->conn->lock);
 	l2cap_chan_del(chan, ECONNREFUSED);
 	l2cap_chan_unlock(chan);
 	l2cap_chan_put(chan);
@@ -7176,6 +7209,8 @@ static void l2cap_data_channel(struct l2cap_conn *conn, u16 cid,
 
 	l2cap_chan_lock(chan);
 
+	lockdep_assert_held(&chan->conn->lock);
+
 	BT_DBG("chan %p, len %d", chan, skb->len);
 
 	/* If we receive data on a fixed channel before the info req/rsp
-- 
cgit v1.2.3


From 4149ba2a806c46853122d1a7063748429d8fc415 Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pav@iki.fi>
Date: Wed, 2 Sep 2026 00:04:35 +0300
Subject: Bluetooth: L2CAP: annotate locking for l2cap_ops callbacks

Annotate current locking context for l2cap_ops callbacks.

Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h | 13 +++++++++----
 net/bluetooth/l2cap_core.c    |  1 +
 2 files changed, 10 insertions(+), 4 deletions(-)

(limited to 'include')

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 3e1e2b36d7b6..efb9b7f422d1 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -653,21 +653,26 @@ struct l2cap_ops {
 	char			*name;
 
 	int			(*new_connection)(struct l2cap_chan *chan,
-						  struct l2cap_chan *new_chan);
+						  struct l2cap_chan *new_chan)
+					__must_hold(&chan->lock)
+					__must_hold(&new_chan->lock);
 	int			(*recv) (struct l2cap_chan * chan,
 					 struct sk_buff *skb);
 	void			(*teardown) (struct l2cap_chan *chan, int err)
 					__must_hold(&chan->lock);
-	void			(*close) (struct l2cap_chan *chan);
+	void			(*close) (struct l2cap_chan *chan)
+					__must_hold(&chan->lock);
 	void			(*state_change) (struct l2cap_chan *chan,
 						 int state, int err);
 	void			(*ready) (struct l2cap_chan *chan)
 					__must_hold(&chan->lock)
 					__must_hold(&chan->conn->lock);
 	void			(*defer) (struct l2cap_chan *chan);
-	void			(*resume) (struct l2cap_chan *chan);
+	void			(*resume) (struct l2cap_chan *chan)
+					__must_hold(&chan->lock);
 	void			(*suspend) (struct l2cap_chan *chan);
-	void			(*set_shutdown) (struct l2cap_chan *chan);
+	void			(*set_shutdown) (struct l2cap_chan *chan)
+					__must_hold(&chan->lock);
 	long			(*get_sndtimeo) (struct l2cap_chan *chan);
 	struct pid		*(*get_peer_pid) (struct l2cap_chan *chan);
 	struct sk_buff		*(*alloc_skb) (struct l2cap_chan *chan,
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 219d92431be0..b7d5fa6f6a83 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4214,6 +4214,7 @@ static inline int l2cap_command_rej(struct l2cap_conn *conn,
 static struct l2cap_chan *l2cap_new_connection(struct l2cap_conn *conn,
 					       struct l2cap_chan *pchan)
 	__must_hold(&conn->lock)
+	__must_hold(&pchan->lock)
 {
 	struct l2cap_chan *chan;
 
-- 
cgit v1.2.3


From 37521ec2f55f3bb32f99ce2e19c73ecba89a8c9c Mon Sep 17 00:00:00 2001
From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date: Fri, 28 Aug 2026 16:04:30 -0400
Subject: Bluetooth: Move H:4 reassembly into the Bluetooth core

h4_recv_buf() is currently implemented in hci_h4.c which is only built as
part of the hci_uart module, and only when CONFIG_BT_HCIUART_H4 is
enabled. That makes the H:4 reassembly logic unusable by drivers which do
not depend on hci_uart, e.g. btusb which needs it to implement Bulk
Serialization Mode.

Move the transport agnostic part into the Bluetooth core as
h4_recv_skb(), which takes a struct hci_dev instead of a struct hci_uart,
along with struct h4_recv_pkt and the H4_RECV_* helpers, and keep
h4_recv_buf() as a thin wrapper for the hci_uart protocols.

Since every Bluetooth driver already depends on the bluetooth module this
introduces no new module dependency and no new Kconfig symbol.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 drivers/bluetooth/hci_h4.c     | 123 ++-----------------------------
 drivers/bluetooth/hci_uart.h   |  39 +---------
 include/net/bluetooth/hci_h4.h |  60 ++++++++++++++++
 net/bluetooth/Makefile         |   2 +-
 net/bluetooth/hci_h4.c         | 160 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 229 insertions(+), 155 deletions(-)
 create mode 100644 include/net/bluetooth/hci_h4.h
 create mode 100644 net/bluetooth/hci_h4.c

(limited to 'include')

diff --git a/drivers/bluetooth/hci_h4.c b/drivers/bluetooth/hci_h4.c
index 767372707498..cbdf51458ec3 100644
--- a/drivers/bluetooth/hci_h4.c
+++ b/drivers/bluetooth/hci_h4.c
@@ -29,6 +29,7 @@
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
+#include <net/bluetooth/hci_h4.h>
 
 #include "hci_uart.h"
 
@@ -112,8 +113,9 @@ static int h4_recv(struct hci_uart *hu, const void *data, int count)
 	if (!h4)
 		return -ENODEV;
 
-	h4->rx_skb = h4_recv_buf(hu, h4->rx_skb, data, count,
-				 h4_recv_pkts, ARRAY_SIZE(h4_recv_pkts));
+	h4->rx_skb = h4_recv_skb(hu->hdev, &hu->alignment, &hu->padding,
+				 h4->rx_skb, data, count, h4_recv_pkts,
+				 ARRAY_SIZE(h4_recv_pkts));
 	if (IS_ERR(h4->rx_skb)) {
 		int err = PTR_ERR(h4->rx_skb);
 		bt_dev_err(hu->hdev, "Frame reassembly failed (%d)", err);
@@ -155,120 +157,7 @@ struct sk_buff *h4_recv_buf(struct hci_uart *hu, struct sk_buff *skb,
 			    const unsigned char *buffer, int count,
 			    const struct h4_recv_pkt *pkts, int pkts_count)
 {
-	u8 alignment = hu->alignment ? hu->alignment : 1;
-	struct hci_dev *hdev = hu->hdev;
-
-	/* Check for error from previous call */
-	if (IS_ERR(skb))
-		skb = NULL;
-
-	while (count) {
-		int i, len;
-
-		/* remove padding bytes from buffer */
-		for (; hu->padding && count > 0; hu->padding--) {
-			count--;
-			buffer++;
-		}
-		if (!count)
-			break;
-
-		if (!skb) {
-			for (i = 0; i < pkts_count; i++) {
-				if (buffer[0] != (&pkts[i])->type)
-					continue;
-
-				skb = bt_skb_alloc((&pkts[i])->maxlen,
-						   GFP_ATOMIC);
-				if (!skb)
-					return ERR_PTR(-ENOMEM);
-
-				hci_skb_pkt_type(skb) = (&pkts[i])->type;
-				hci_skb_expect(skb) = (&pkts[i])->hlen;
-				break;
-			}
-
-			/* Check for invalid packet type */
-			if (!skb)
-				return ERR_PTR(-EILSEQ);
-
-			count -= 1;
-			buffer += 1;
-		}
-
-		len = min_t(uint, hci_skb_expect(skb) - skb->len, count);
-		skb_put_data(skb, buffer, len);
-
-		count -= len;
-		buffer += len;
-
-		/* Check for partial packet */
-		if (skb->len < hci_skb_expect(skb))
-			continue;
-
-		for (i = 0; i < pkts_count; i++) {
-			if (hci_skb_pkt_type(skb) == (&pkts[i])->type)
-				break;
-		}
-
-		if (i >= pkts_count) {
-			kfree_skb(skb);
-			return ERR_PTR(-EILSEQ);
-		}
-
-		if (skb->len == (&pkts[i])->hlen) {
-			u16 dlen;
-
-			switch ((&pkts[i])->lsize) {
-			case 0:
-				/* No variable data length */
-				dlen = 0;
-				break;
-			case 1:
-				/* Single octet variable length */
-				dlen = skb->data[(&pkts[i])->loff];
-				hci_skb_expect(skb) += dlen;
-
-				if (skb_tailroom(skb) < dlen) {
-					kfree_skb(skb);
-					return ERR_PTR(-EMSGSIZE);
-				}
-				break;
-			case 2:
-				/* Double octet variable length */
-				dlen = get_unaligned_le16(skb->data +
-							  (&pkts[i])->loff);
-				hci_skb_expect(skb) += dlen;
-
-				if (skb_tailroom(skb) < dlen) {
-					kfree_skb(skb);
-					return ERR_PTR(-EMSGSIZE);
-				}
-				break;
-			default:
-				/* Unsupported variable length */
-				kfree_skb(skb);
-				return ERR_PTR(-EILSEQ);
-			}
-
-			if (!dlen) {
-				hu->padding = (skb->len + 1) % alignment;
-				hu->padding = (alignment - hu->padding) % alignment;
-
-				/* No more data, complete frame */
-				(&pkts[i])->recv(hdev, skb);
-				skb = NULL;
-			}
-		} else {
-			hu->padding = (skb->len + 1) % alignment;
-			hu->padding = (alignment - hu->padding) % alignment;
-
-			/* Complete frame */
-			(&pkts[i])->recv(hdev, skb);
-			skb = NULL;
-		}
-	}
-
-	return skb;
+	return h4_recv_skb(hu->hdev, &hu->alignment, &hu->padding, skb, buffer,
+			   count, pkts, pkts_count);
 }
 EXPORT_SYMBOL_GPL(h4_recv_buf);
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index 48ac7ca9334e..7fbe8dffab98 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -8,6 +8,8 @@
  *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
  */
 
+#include <net/bluetooth/hci_h4.h>
+
 #ifndef N_HCI
 #define N_HCI	15
 #endif
@@ -121,43 +123,6 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable);
 void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
 			 unsigned int oper_speed);
 
-struct h4_recv_pkt {
-	u8  type;	/* Packet type */
-	u8  hlen;	/* Header length */
-	u8  loff;	/* Data length offset in header */
-	u8  lsize;	/* Data length field size */
-	u16 maxlen;	/* Max overall packet length */
-	int (*recv)(struct hci_dev *hdev, struct sk_buff *skb);
-};
-
-#define H4_RECV_ACL \
-	.type = HCI_ACLDATA_PKT, \
-	.hlen = HCI_ACL_HDR_SIZE, \
-	.loff = 2, \
-	.lsize = 2, \
-	.maxlen = HCI_MAX_FRAME_SIZE \
-
-#define H4_RECV_SCO \
-	.type = HCI_SCODATA_PKT, \
-	.hlen = HCI_SCO_HDR_SIZE, \
-	.loff = 2, \
-	.lsize = 1, \
-	.maxlen = HCI_MAX_SCO_SIZE
-
-#define H4_RECV_EVENT \
-	.type = HCI_EVENT_PKT, \
-	.hlen = HCI_EVENT_HDR_SIZE, \
-	.loff = 1, \
-	.lsize = 1, \
-	.maxlen = HCI_MAX_EVENT_SIZE
-
-#define H4_RECV_ISO \
-	.type = HCI_ISODATA_PKT, \
-	.hlen = HCI_ISO_HDR_SIZE, \
-	.loff = 2, \
-	.lsize = 2, \
-	.maxlen = HCI_MAX_FRAME_SIZE \
-
 #ifdef CONFIG_BT_HCIUART_H4
 int h4_init(void);
 int h4_deinit(void);
diff --git a/include/net/bluetooth/hci_h4.h b/include/net/bluetooth/hci_h4.h
new file mode 100644
index 000000000000..a37e7df8c9ce
--- /dev/null
+++ b/include/net/bluetooth/hci_h4.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *  Bluetooth HCI H:4 packet reassembly
+ *
+ *  Copyright (C) 2000-2001  Qualcomm Incorporated
+ *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
+ *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
+ */
+
+#ifndef __HCI_H4_H
+#define __HCI_H4_H
+
+#include <linux/skbuff.h>
+#include <linux/types.h>
+
+struct hci_dev;
+
+struct h4_recv_pkt {
+	u8  type;	/* Packet type */
+	u8  hlen;	/* Header length */
+	u8  loff;	/* Data length offset in header */
+	u8  lsize;	/* Data length field size */
+	u16 maxlen;	/* Max overall packet length */
+	int (*recv)(struct hci_dev *hdev, struct sk_buff *skb);
+};
+
+#define H4_RECV_ACL \
+	.type = HCI_ACLDATA_PKT, \
+	.hlen = HCI_ACL_HDR_SIZE, \
+	.loff = 2, \
+	.lsize = 2, \
+	.maxlen = HCI_MAX_FRAME_SIZE \
+
+#define H4_RECV_SCO \
+	.type = HCI_SCODATA_PKT, \
+	.hlen = HCI_SCO_HDR_SIZE, \
+	.loff = 2, \
+	.lsize = 1, \
+	.maxlen = HCI_MAX_SCO_SIZE
+
+#define H4_RECV_EVENT \
+	.type = HCI_EVENT_PKT, \
+	.hlen = HCI_EVENT_HDR_SIZE, \
+	.loff = 1, \
+	.lsize = 1, \
+	.maxlen = HCI_MAX_EVENT_SIZE
+
+#define H4_RECV_ISO \
+	.type = HCI_ISODATA_PKT, \
+	.hlen = HCI_ISO_HDR_SIZE, \
+	.loff = 2, \
+	.lsize = 2, \
+	.maxlen = HCI_MAX_FRAME_SIZE \
+
+struct sk_buff *h4_recv_skb(struct hci_dev *hdev, u8 *alignment, u8 *padding,
+			    struct sk_buff *skb, const unsigned char *buffer,
+			    int count, const struct h4_recv_pkt *pkts,
+			    int pkts_count);
+
+#endif /* __HCI_H4_H */
diff --git a/net/bluetooth/Makefile b/net/bluetooth/Makefile
index ff466ea97436..b78ad98864d4 100644
--- a/net/bluetooth/Makefile
+++ b/net/bluetooth/Makefile
@@ -14,7 +14,7 @@ bluetooth_6lowpan-y := 6lowpan.o
 bluetooth-y := af_bluetooth.o hci_core.o hci_conn.o hci_event.o mgmt.o \
 	hci_sock.o hci_sysfs.o l2cap_core.o l2cap_sock.o smp.o lib.o \
 	ecdh_helper.o mgmt_util.o mgmt_config.o hci_codec.o eir.o hci_sync.o \
-	hci_drv.o
+	hci_drv.o hci_h4.o
 
 bluetooth-$(CONFIG_DEV_COREDUMP) += coredump.o
 
diff --git a/net/bluetooth/hci_h4.c b/net/bluetooth/hci_h4.c
new file mode 100644
index 000000000000..86f809018062
--- /dev/null
+++ b/net/bluetooth/hci_h4.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Bluetooth HCI H:4 packet reassembly
+ *
+ *  Copyright (C) 2000-2001  Qualcomm Incorporated
+ *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
+ *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
+ */
+
+#include <linux/export.h>
+#include <linux/skbuff.h>
+#include <linux/unaligned.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+#include <net/bluetooth/hci_h4.h>
+
+/* h4_recv_skb - Reassemble H:4 framed packets
+ * @hdev: HCI device the packets are received on
+ * @alignment: optional packet alignment, NULL or 0 means no alignment
+ * @padding: optional padding state carried over between calls
+ * @skb: partially received packet from a previous call, may be NULL or an
+ *	 ERR_PTR returned by a previous call
+ * @buffer: buffer holding the received data
+ * @count: number of bytes in @buffer
+ * @pkts: table of supported packet types
+ * @pkts_count: number of entries in @pkts
+ *
+ * Returns the partially received packet to be passed to the next call, or an
+ * ERR_PTR on error. The returned value can be fed back into this function as
+ * is, but must be checked with IS_ERR() before being freed.
+ */
+struct sk_buff *h4_recv_skb(struct hci_dev *hdev, u8 *alignment, u8 *padding,
+			    struct sk_buff *skb, const unsigned char *buffer,
+			    int count, const struct h4_recv_pkt *pkts,
+			    int pkts_count)
+{
+	u8 align = alignment && *alignment ? *alignment : 1;
+
+	/* Check for error from previous call */
+	if (IS_ERR(skb))
+		skb = NULL;
+
+	while (count) {
+		int i, len;
+
+		/* remove padding bytes from buffer */
+		if (padding) {
+			for (; (*padding) && count > 0; (*padding)--) {
+				count--;
+				buffer++;
+			}
+		}
+
+		if (!count)
+			break;
+
+		if (!skb) {
+			for (i = 0; i < pkts_count; i++) {
+				if (buffer[0] != pkts[i].type)
+					continue;
+
+				skb = bt_skb_alloc(pkts[i].maxlen,
+						   GFP_ATOMIC);
+				if (!skb)
+					return ERR_PTR(-ENOMEM);
+
+				hci_skb_pkt_type(skb) = pkts[i].type;
+				hci_skb_expect(skb) = pkts[i].hlen;
+				break;
+			}
+
+			/* Check for invalid packet type */
+			if (!skb)
+				return ERR_PTR(-EILSEQ);
+
+			count -= 1;
+			buffer += 1;
+		}
+
+		len = min_t(uint, hci_skb_expect(skb) - skb->len, count);
+		skb_put_data(skb, buffer, len);
+
+		count -= len;
+		buffer += len;
+
+		/* Check for partial packet */
+		if (skb->len < hci_skb_expect(skb))
+			continue;
+
+		for (i = 0; i < pkts_count; i++) {
+			if (hci_skb_pkt_type(skb) == pkts[i].type)
+				break;
+		}
+
+		if (i >= pkts_count) {
+			kfree_skb(skb);
+			return ERR_PTR(-EILSEQ);
+		}
+
+		if (skb->len == pkts[i].hlen) {
+			u16 dlen;
+
+			switch (pkts[i].lsize) {
+			case 0:
+				/* No variable data length */
+				dlen = 0;
+				break;
+			case 1:
+				/* Single octet variable length */
+				dlen = skb->data[pkts[i].loff];
+				hci_skb_expect(skb) += dlen;
+
+				if (skb_tailroom(skb) < dlen) {
+					kfree_skb(skb);
+					return ERR_PTR(-EMSGSIZE);
+				}
+				break;
+			case 2:
+				/* Double octet variable length */
+				dlen = get_unaligned_le16(skb->data +
+							  pkts[i].loff);
+				hci_skb_expect(skb) += dlen;
+
+				if (skb_tailroom(skb) < dlen) {
+					kfree_skb(skb);
+					return ERR_PTR(-EMSGSIZE);
+				}
+				break;
+			default:
+				/* Unsupported variable length */
+				kfree_skb(skb);
+				return ERR_PTR(-EILSEQ);
+			}
+
+			if (!dlen) {
+				if (padding) {
+					*padding = (skb->len + 1) % align;
+					*padding = (align - *padding) % align;
+				}
+
+				/* No more data, complete frame */
+				pkts[i].recv(hdev, skb);
+				skb = NULL;
+			}
+		} else {
+			if (padding) {
+				*padding = (skb->len + 1) % align;
+				*padding = (align - *padding) % align;
+			}
+
+			/* Complete frame */
+			pkts[i].recv(hdev, skb);
+			skb = NULL;
+		}
+	}
+
+	return skb;
+}
+EXPORT_SYMBOL_GPL(h4_recv_skb);
-- 
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