kernel/git/stable/linux.git/drivers/net/vxlan, branch linux-6.12.y

vxlan: mdb: Fix use-after-free in vxlan_mdb_flush()

2026-09-14T11:32:51+00:00

[ Upstream commit bc2dc66a6693a78f8c1e6ca2dbebd50f16e2c366 ] vxlan_mdb_flush() iterates over the MDB entries using hlist_for_each_entry_safe(), which only tolerates the removal of the current entry. Contrary to the comment above the loop, the removal of an entry can trigger the removal of another entry. Flushing the remotes of a (*, G) entry also removes the (S, G) entries that were created for its source list, once they are left without remotes: vxlan_mdb_remotes_flush() -> vxlan_mdb_remote_del() -> vxlan_mdb_remote_srcs_del() -> vxlan_mdb_remote_src_del() -> vxlan_mdb_remote_src_fwd_del() -> __vxlan_mdb_del() -> vxlan_mdb_entry_put() Such an entry can be located after the (*, G) entry in the list, as vxlan_mdb_entry_get() returns an existing entry without moving it to the head of the list. This order is obtained by adding the (S, G) entry before the (*, G) entry, the latter with NLM_F_REPLACE, as the addition of the source otherwise fails with -EEXIST. The (S, G) entry is then the entry saved by hlist_for_each_entry_safe() and it is freed while the (*, G) entry is processed. The next iteration calls hlist_del() on it again, writing LIST_POISON1 to LIST_POISON2 [1]. Besides device deletion, the flush is also reachable from RTM_DELMDB with NLM_F_BULK. Fix by re-reading the next entry after the remotes were flushed. The current entry cannot be removed by this flush, as source lists can only be configured on (*, G) entries and the removed entries are (S, G) entries. It is therefore still linked and its next pointer reflects the removals. [1] BUG: KASAN: wild-memory-access in vxlan_mdb_entry_put.part.0+0x328/0x588 Write of size 8 at addr dead000000000122 by task ip/327 CPU: 3 UID: 1000 PID: 327 Comm: ip Not tainted 7.2.0-rc7 #2 PREEMPT Call trace: vxlan_mdb_entry_put.part.0+0x328/0x588 vxlan_mdb_flush+0x1d8/0x25c vxlan_mdb_fini+0x8c/0x100 vxlan_uninit+0x1c/0x7c unregister_netdevice_many_notify+0x954/0xd4c rtnl_dellink+0x210/0x530 rtnetlink_rcv_msg+0x434/0x4d0 netlink_rcv_skb+0xc4/0x204 rtnetlink_rcv+0x18/0x24 netlink_unicast+0x4b8/0x548 netlink_sendmsg+0x29c/0x560 ____sys_sendmsg+0x390/0x3ec ___sys_sendmsg+0x114/0x188 __sys_sendmsg+0xf0/0x178 __arm64_sys_sendmsg+0x48/0x60 invoke_syscall.constprop.0+0x58/0x180 el0_svc_common.constprop.0+0x74/0x140 do_el0_svc+0x30/0x40 el0_svc+0x38/0x98 el0t_64_sync_handler+0xa0/0xe4 el0t_64_sync+0x198/0x19c Fixes: a3a48de5eade ("vxlan: mdb: Add MDB control path support") Signed-off-by: Baul Lee Reviewed-by: Nikolay Aleksandrov Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260814153547.29567-1-baul.lee@xbow.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

vxlan: vnifilter: enforce exact length of GROUP/GROUP6 attributes

2026-09-14T11:32:50+00:00

[ Upstream commit 984f831dda31b3a18f47454cf64989f65402879e ] The VXLAN VNI filter entry policy declares the GROUP/GROUP6 address attributes as NLA_BINARY with only a maximum length, so validate_nla() accepts a payload shorter than the address. The GROUP consumer reads it with nla_get_in_addr(), an unconditional 4-byte load, so a short attribute over-reads up to 3 bytes of uninitialised slab data, which are stored into remote_ip and echoed back via RTM_GETTUNNEL, disclosing kernel memory. Switch both entries to NLA_POLICY_EXACT_LEN() so the validator rejects any GROUP/GROUP6 that is not exactly 4 / 16 bytes; a valid address is always sent at full width. Fixes: f9c4bb0b245c ("vxlan: vni filtering support on collect metadata device") Reported-by: Weiming Shi Signed-off-by: Xiang Mei Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260812215341.763123-1-xmei5@asu.edu Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

vxlan: keep the last remote linked during FDB flush

2026-09-02T12:31:01+00:00

commit d5d4a7b538b52db63927773a8905fcd9f78a42e2 upstream. A non-nexthop FDB entry is expected to have at least one remote while it remains reachable through the FDB hash table. A filtered bulk flush violates this invariant when every remote matches: It unlinks the last remote in vxlan_fdb_dst_destroy() and only afterwards tells vxlan_flush() to destroy the parent FDB entry. An RCU reader can find the parent during this interval. first_remote_rcu() then applies list_entry_rcu() to the empty list head, producing an invalid remote pointer that the receive learning path can read from and write to. When a matching remote is the sole remaining remote, leave it linked and ask the caller to destroy the entire FDB entry. vxlan_fdb_destroy() keeps the remote attached while sending the deletion notification and removing the parent from the lookup structures. Fixes: c499fccb71cb ("vxlan: vxlan_core: Support FDB flushing by destination VNI") Cc: stable@vger.kernel.org Signed-off-by: Kyle Zeng Co-developed-by: David Lee Signed-off-by: David Lee Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260810144115.821654-1-david.lee@trailofbits.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

vxlan: use pskb_network_may_pull() for transmit path header pulls

2026-08-23T12:22:47+00:00

[ Upstream commit b9553558b48db54ac9273e6b98d7263ef5c1a329 ] In vxlan_xmit(), arp_reduce(), and vxlan_mdb_entry_skb_get(), pskb_may_pull() was being called to verify the availability of network layer headers (ARP, IPv6/ND, IP/IPv6 MDB keys). However, during transmit skb->data points to the MAC header, so skb_network_offset(skb) is ETH_HLEN (14 bytes). Using pskb_may_pull(skb, len) only checks len bytes from skb->data rather than skb_network_offset(skb) + len, which can leave part of the network header in non-linear frags. Replace these remaining pskb_may_pull() calls with pskb_network_may_pull() to properly account for the MAC header offset. Fixes: e4f67addf158 ("add DOVE extensions for VXLAN") Fixes: f564f45c4518 ("vxlan: add ipv6 proxy support") Fixes: 0f83e69f44bf ("vxlan: Add MDB data path support") Signed-off-by: Eric Dumazet Cc: stable@vger.kernel.org Reviewed-by: Vadim Fedorenko Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260723144249.759100-6-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

vxlan: Handle stats using NETDEV_PCPU_STAT_DSTATS.

2026-08-23T12:22:47+00:00

[ Upstream commit be226352e8dc77d3313c096b2d8e7f69bf6980fc ] VXLAN uses the TSTATS infrastructure (dev_sw_netstats_*()) for RX and TX packet counters. It also uses the device core stats (dev_core_stats_*()) for RX and TX drops. Let's consolidate that using the DSTATS infrastructure, which can handle both packet counters and packet drops. Statistics that don't fit DSTATS are still updated atomically with DEV_STATS_INC(). While there, convert the "len" variable of vxlan_encap_bypass() to unsigned int, to respect the types of skb->len and dev_dstats_[rt]x_add(). Signed-off-by: Guillaume Nault Link: https://patch.msgid.link/145558b184b3cda77911ca5682b6eb83c3ffed8e.1733313925.git.gnault@redhat.com Signed-off-by: Jakub Kicinski Stable-dep-of: b9553558b48d ("vxlan: use pskb_network_may_pull() for transmit path header pulls") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

vxlan: do not arm the ageing timer on a device that is down

2026-08-19T16:14:28+00:00

commit b37971686ec59fb027fa4910ba16805e68fddb97 upstream. vxlan_changelink() arms vxlan->age_timer whenever the requested ageing interval differs from the configured one: if (conf.age_interval != vxlan->cfg.age_interval) mod_timer(&vxlan->age_timer, jiffies); There is no netif_running() test, so the timer is armed even on a device that was never brought up. The only synchronous cancel in the driver is the timer_delete_sync() in vxlan_stop(), which is .ndo_stop. netif_close_many() drops devices without IFF_UP before __dev_close_many() runs, so that cancel is skipped for such a device. vxlan_setup() sets dev->needs_free_netdev = true and age_timer is a member of struct vxlan_dev, so free_netdev() releases the allocation the timer lives in while it is still queued on a timer_base. expire_timers() unlinks the entry before it loads timer->function, so the timer core writes through the freed object's list pointers: BUG: KASAN: slab-use-after-free in __run_timers+0x208/0x654 Write of size 8 at addr ffff00001adace68 by task true/192 __asan_store8+0x84/0xac __run_timers+0x208/0x654 run_timer_softirq+0x154/0x18c Allocated by task 189: alloc_netdev_mqs+0x64/0x720 rtnl_create_link+0x4ac/0x520 rtnl_newlink+0x758/0xd00 Freed by task 191: netdev_release+0x40/0x58 netdev_run_todo+0x4a4/0x8c0 rtnl_dellink+0x200/0x4e8 The rtnl operations involved are netns-scoped, so an unprivileged user can perform them in a new user and network namespace. Arming the timer on a down device never had an effect: vxlan_cleanup() returns early on !netif_running(), and vxlan_open() arms the timer for any non-zero interval once the device is brought up. Add the missing test. Discovered by XBOW, triaged by Baul Lee Fixes: 40051c4dcad5 ("vxlan: Allow changing ageing time") Cc: stable@vger.kernel.org Signed-off-by: Baul Lee Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260809111829.78834-1-baul.lee@xbow.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

vxlan: use pskb_network_may_pull() in route_shortcircuit()

2026-08-09T18:23:15+00:00

commit 26bb2dd0a8839617e2c79ffbbe1923f8e4bab9fb upstream. route_shortcircuit() currently calls pskb_may_pull(skb, sizeof(struct iphdr)) (or ipv6hdr), which checks if bytes are available starting from skb->data. However, in vxlan_xmit(), skb->data points to the MAC header, so skb_network_offset(skb) is ETH_HLEN (14 bytes). Using pskb_may_pull(skb, 20) only checks 20 bytes from skb->data (which is 14 bytes MAC header + 6 bytes of IP header), leaving the rest of the IP header potentially un-pulled in non-linear frags. Subsequent dereferences of ip_hdr(skb)->daddr can read beyond the pulled linear buffer length. Fix this by using pskb_network_may_pull(), which adds skb_network_offset(skb) to the length check to ensure the full network header is present in the linear buffer. Fixes: e4f67addf158 ("add DOVE extensions for VXLAN") Cc: stable@vger.kernel.org Signed-off-by: Eric Dumazet Reviewed-by: Vadim Fedorenko Link: https://patch.msgid.link/20260723144249.759100-5-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

vxlan: use neigh_ha_snapshot() in route_shortcircuit()

2026-08-09T18:23:15+00:00

commit 8eca411347e1d38964f9ed2c8d3b6ab0e7e4473d upstream. The neighbour hardware address n->ha can be updated asynchronously by the neighbour subsystem, protected by n->ha_lock seqlock. Reading n->ha without holding the seqlock loop can lead to torn reads or reading a partially updated MAC address. Use neigh_ha_snapshot() in route_shortcircuit() to safely copy n->ha under read_seqbegin()/read_seqretry() lock protection before using it. Note that arp_reduce() and neigh_reduce() seem to have the same issue left for future patches. Fixes: e4f67addf158 ("add DOVE extensions for VXLAN") Cc: stable@vger.kernel.org Signed-off-by: Eric Dumazet Reviewed-by: Vadim Fedorenko Link: https://patch.msgid.link/20260723144249.759100-4-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

vxlan: unclone skb head before modifying eth header in route_shortcircuit()

2026-08-09T18:23:15+00:00

commit 760d36e737f2b3867762f42af36c663f55babcc4 upstream. When route_shortcircuit() performs L3 short-circuit routing, it modifies the Ethernet header of the skb in-place: memcpy(eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest, dev->addr_len); memcpy(eth_hdr(skb)->h_dest, n->ha, dev->addr_len); If the incoming skb is cloned (for example by packet sockets, tcpdump, or dev_queue_xmit), modifying the Ethernet header without uncloning can corrupt the packet header for other readers holding a reference to the cloned skb. Ensure the skb header is writable and unshared by calling skb_cow_head(skb, 0) prior to updating the Ethernet header. If skb_cow_head() fails, abort short-circuiting and return false to allow standard packet processing fallback. Fixes: e4f67addf158 ("add DOVE extensions for VXLAN") Cc: stable@vger.kernel.org Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260723144249.759100-3-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

vxlan: re-fetch eth header after route_shortcircuit()

2026-08-09T18:23:15+00:00

commit 1395a676ec15a0a02a2a6d86602324f2d5fd41d5 upstream. Before route_shortcircuit(), the eth header pointer is cached from eth_hdr(skb). Inside route_shortcircuit(), pskb_may_pull() can be called, which may reallocate skb->head. In this case, returning to vxlan_xmit() leaves the cached eth pointer pointing to freed memory, leading to a use-after-free when dereferencing eth->h_dest. Fix this by updating eth = eth_hdr(skb) after calling route_shortcircuit(). Fixes: ae8840825605 ("VXLAN: Allow L2 redirection with L3 switching") Cc: stable@vger.kernel.org Signed-off-by: Eric Dumazet Reviewed-by: Vadim Fedorenko Link: https://patch.msgid.link/20260723144249.759100-2-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman