kernel/git/stable/linux.git/drivers/net/bonding, branch linux-6.1.y

bonding: initialize err for empty target lists

2026-09-14T11:25:44+00:00

[ Upstream commit 8ccc9bf9afeeb46a437081c07154fbf5964682b2 ] Empty NLA_NESTED attributes are valid, and bonding uses them to clear the ARP and NS target lists. When either target attribute is empty, nla_for_each_nested() does not execute, so err retains an uninitialized value before it is tested. The request can consequently return an unpredictable error after clearing the targets. Initialize err to zero so an empty target list completes successfully. Non-empty lists still propagate errors from __bond_opt_set() unchanged. This issue was found by a static analysis checker and confirmed by manual source review. Fixes: 4fb0ef585eb2 ("bonding: convert arp_ip_target to use the new option API") Signed-off-by: Ruoyu Wang Reviewed-by: Nikolay Aleksandrov Acked-by: Jay Vosburgh Reviewed-by: Hangbin Liu Link: https://patch.msgid.link/20260813153126.3952893-1-ruoyuw560@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bonding: fix use-after-free in bond_xmit_broadcast()

2026-08-23T12:18:20+00:00

commit 2884bf72fb8f03409e423397319205de48adca16 upstream. bond_xmit_broadcast() reuses the original skb for the last slave (determined by bond_is_last_slave()) and clones it for others. Concurrent slave enslave/release can mutate the slave list during RCU-protected iteration, changing which slave is "last" mid-loop. This causes the original skb to be double-consumed (double-freed). Replace the racy bond_is_last_slave() check with a simple index comparison (i + 1 == slaves_count) against the pre-snapshot slave count taken via READ_ONCE() before the loop. This preserves the zero-copy optimization for the last slave while making the "last" determination stable against concurrent list mutations. The UAF can trigger the following crash: ================================================================== BUG: KASAN: slab-use-after-free in skb_clone Read of size 8 at addr ffff888100ef8d40 by task exploit/147 CPU: 1 UID: 0 PID: 147 Comm: exploit Not tainted 7.0.0-rc3+ #4 PREEMPTLAZY Call Trace: dump_stack_lvl (lib/dump_stack.c:123) print_report (mm/kasan/report.c:379 mm/kasan/report.c:482) kasan_report (mm/kasan/report.c:597) skb_clone (include/linux/skbuff.h:1724 include/linux/skbuff.h:1792 include/linux/skbuff.h:3396 net/core/skbuff.c:2108) bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5334) bond_start_xmit (drivers/net/bonding/bond_main.c:5567 drivers/net/bonding/bond_main.c:5593) dev_hard_start_xmit (include/linux/netdevice.h:5325 include/linux/netdevice.h:5334 net/core/dev.c:3871 net/core/dev.c:3887) __dev_queue_xmit (include/linux/netdevice.h:3601 net/core/dev.c:4838) ip6_finish_output2 (include/net/neighbour.h:540 include/net/neighbour.h:554 net/ipv6/ip6_output.c:136) ip6_finish_output (net/ipv6/ip6_output.c:208 net/ipv6/ip6_output.c:219) ip6_output (net/ipv6/ip6_output.c:250) ip6_send_skb (net/ipv6/ip6_output.c:1985) udp_v6_send_skb (net/ipv6/udp.c:1442) udpv6_sendmsg (net/ipv6/udp.c:1733) __sys_sendto (net/socket.c:730 net/socket.c:742 net/socket.c:2206) __x64_sys_sendto (net/socket.c:2209) do_syscall_64 (arch/x86/entry/syscall_64.c:63 arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) Allocated by task 147: Freed by task 147: The buggy address belongs to the object at ffff888100ef8c80 which belongs to the cache skbuff_head_cache of size 224 The buggy address is located 192 bytes inside of freed 224-byte region [ffff888100ef8c80, ffff888100ef8d60) Memory state around the buggy address: ffff888100ef8c00: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff888100ef8c80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888100ef8d00: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff888100ef8d80: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff888100ef8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Fixes: 4e5bd03ae346 ("net: bonding: fix bond_xmit_broadcast return value error bug") Reported-by: Weiming Shi Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260326075553.3960562-1-xmei5@asu.edu Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor

2026-08-19T15:16:22+00:00

[ Upstream commit 683c6ba6e58e6ed1037831ea97dd58d9c0e76b8d ] bond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and takes RTNL via rtnl_trylock() before undoing the promiscuity it set on the active slave. In that window the active slave can change under RTNL (RTM_DELLINK -> __bond_release_one() -> bond_alb_handle_active_change()), which already drops the promiscuity and clears primary_is_promisc. The monitor still acts on the stale decision: if the slave was removed with no failover, curr_active_slave is now NULL and the deref faults; if it failed over, the stale dev_set_promiscuity(-1) underflows the new slave's promiscuity counter and pins it in IFF_PROMISC. Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: b42 bond_alb_monitor RIP: 0010:bond_alb_monitor (drivers/net/bonding/bond_alb.c:1600) process_one_work (kernel/workqueue.c:3322) worker_thread (kernel/workqueue.c:3486) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) Kernel panic - not syncing: Fatal exception Re-check primary_is_promisc (and curr_active_slave) after taking RTNL so the monitor only undoes an increment it still owns. The other bonding monitors already re-read state under RTNL in their commit phase (bond_miimon_commit/bond_ab_arp_commit); bond_alb_monitor() was the only one acting on the pre-trylock decision. Fixes: d0e81b7e2246 ("bonding: Acquire correct locks in alb for promisc change") Reported-by: AutonomousCodeSecurity@microsoft.com Signed-off-by: Xiang Mei (Microsoft) Reviewed-by: Nikolay Aleksandrov Acked-by: Jay Vosburgh Link: https://patch.msgid.link/20260725233930.2957317-1-xmei5@asu.edu Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

bonding: fix devconf_all NULL dereference when IPv6 is disabled

2026-08-19T15:16:00+00:00

[ Upstream commit 1c975de3343cdef506f2eecc833cc1f14b0401c4 ] When booting with the 'ipv6.disable=1' parameter, the devconf_all is never initialized because inet6_init() exits before addrconf_init() is called which initializes it. bond_send_validate(), however, will still call bond_ns_send_all() even ipv6 is indeed disabled. It will lead to NULL derefence of net->ipv6.devconf_all in ip6_pol_route(). BUG: kernel NULL pointer dereference, address: 000000000000000c [...] Workqueue: bond0 bond_arp_monitor [bonding] RIP: 0010:ip6_pol_route+0x69/0x480 [...] Call Trace: ? srso_return_thunk+0x5/0x5f ? __pfx_ip6_pol_route_output+0x10/0x10 fib6_rule_lookup+0xfe/0x260 ? wakeup_preempt+0x8a/0x90 ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f ? sched_balance_rq+0x369/0x810 ip6_route_output_flags+0xd7/0x170 bond_ns_send_all+0xde/0x280 [bonding] bond_ab_arp_probe+0x296/0x320 [bonding] ? srso_return_thunk+0x5/0x5f bond_activebackup_arp_mon+0xb4/0x2c0 [bonding] process_one_work+0x196/0x370 worker_thread+0x1af/0x320 ? srso_return_thunk+0x5/0x5f ? __pfx_worker_thread+0x10/0x10 kthread+0xe3/0x120 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x199/0x260 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 Fix this by adding ipv6_mod_enabled() condition check in the caller. Fixes: 4e24be018eb9 ("bonding: add new parameter ns_targets") Signed-off-by: Qianheng Peng Signed-off-by: Zhaolong Zhang Reviewed-by: Hangbin Liu Link: https://patch.msgid.link/20260707010622.487333-1-zhangzl2013@126.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

bonding: 3ad: fix mux port state on oper down

2026-07-24T13:54:41+00:00

[ Upstream commit 807afc7544b865d4d09068a415fd5b71bf5665cc ] When the bonding interface has carrier down due to the absence of usable slaves and a slave transitions from down to up, the bonding interface briefly goes carrier up, then down again, and finally up once LACP negotiates collecting and distributing on the port. When lacp_strict mode is on, the interface should not transition to carrier up until LACP negotiation is complete. This happens because the actor and partner port states remain in Collecting_Distributing when the port goes down. When the port comes back up, it temporarily remains in this state until LACP renegotiation occurs. Previously this was mostly cosmetic, but since the bonding carrier state may depend on the LACP negotiation state, it causes the interface to flap. According to IEEE 802.3ad-2000 and IEEE 802.1ax-2014, Collecting and Distributing should be reset when a port goes down: - In the Receive state machine, port_enabled == FALSE causes a transition to the PORT_DISABLED state, which is expected to clear Partner_Oper_Port_State.Synchronization. - In the Mux state machine, Partner_Oper_Port_State.Synchronization == FALSE causes a transition to the ATTACHED state, which disables Collecting and Distributing. However, Partner_Oper_Port_State.Synchronization is not cleared in the PORT_DISABLED state. Clear Partner_Oper_Port_State.Synchronization in the Receive PORT_DISABLED state. Fixes: 655f8919d549 ("bonding: add min links parameter to 802.3ad") Signed-off-by: Louis Scalbert Acked-by: Jay Vosburgh Link: https://patch.msgid.link/20260603150331.1919611-6-louis.scalbert@6wind.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bonding: fix NULL pointer dereference in bond_do_ioctl()

2026-06-19T11:37:16+00:00

commit a764b0e8317a863006e05732e1aefe821b9d8c2d upstream. In bond_do_ioctl(), slave_dev is obtained via __dev_get_by_name() which can return NULL if the requested interface name does not exist. However, the subsequent slave_dbg() call is placed before the NULL check: slave_dev = __dev_get_by_name(net, ifr->ifr_slave); slave_dbg(bond_dev, slave_dev, "slave_dev=%p:\n", slave_dev); //here if (!slave_dev) return -ENODEV; The slave_dbg() macro expands to netdev_dbg(bond_dev, "(slave %s): " fmt, (slave_dev)->name, ...) which unconditionally dereferences slave_dev->name before the NULL check is performed. This results in a NULL pointer dereference kernel oops when a user calls bonding ioctl (e.g. SIOCBONDENSLAVE, SIOCBONDRELEASE, etc.) with a non-existent slave interface name. This is reachable from userspace via the bonding ioctl interface with CAP_NET_ADMIN capability, making it a potential local denial-of-service vector. Fix by moving the slave_dbg() call after the NULL check. Fixes: e2a7420df2e0 ("bonding/main: convert to using slave printk macros") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: ZhaoJinming Link: https://patch.msgid.link/20260601085649.4029067-1-zhaojinming@uniontech.com Signed-off-by: Paolo Abeni Signed-off-by: Greg Kroah-Hartman

bpf/bonding: reject vlan+srcmac xmit_hash_policy change when XDP is loaded

2026-06-19T11:37:07+00:00

[ Upstream commit 479d589b40b836442bbdadc3fdb37f001bb67f26 ] bond_option_mode_set() already rejects mode changes that would make a loaded XDP program incompatible via bond_xdp_check(). However, bond_option_xmit_hash_policy_set() has no such guard. For 802.3ad and balance-xor modes, bond_xdp_check() returns false when xmit_hash_policy is vlan+srcmac, because the 802.1q payload is usually absent due to hardware offload. This means a user can: 1. Attach a native XDP program to a bond in 802.3ad/balance-xor mode with a compatible xmit_hash_policy (e.g. layer2+3). 2. Change xmit_hash_policy to vlan+srcmac while XDP remains loaded. This leaves bond->xdp_prog set but bond_xdp_check() now returning false for the same device. When the bond is later destroyed, dev_xdp_uninstall() calls bond_xdp_set(dev, NULL, NULL) to remove the program, which hits the bond_xdp_check() guard and returns -EOPNOTSUPP, triggering: WARN_ON(dev_xdp_install(dev, mode, bpf_op, NULL, 0, NULL)) Fix this by rejecting xmit_hash_policy changes to vlan+srcmac when an XDP program is loaded on a bond in 802.3ad or balance-xor mode. commit 39a0876d595b ("net, bonding: Disallow vlan+srcmac with XDP") introduced bond_xdp_check() which returns false for 802.3ad/balance-xor modes when xmit_hash_policy is vlan+srcmac. The check was wired into bond_xdp_set() to reject XDP attachment with an incompatible policy, but the symmetric path -- preventing xmit_hash_policy from being changed to an incompatible value after XDP is already loaded -- was left unguarded in bond_option_xmit_hash_policy_set(). Note: commit 094ee6017ea0 ("bonding: check xdp prog when set bond mode") later added a similar guard to bond_option_mode_set(), but bond_option_xmit_hash_policy_set() remained unprotected. Reported-by: syzbot+5a287bcdc08104bc3132@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6995aff6.050a0220.2eeac1.014e.GAE@google.com/T/ Fixes: 39a0876d595b ("net, bonding: Disallow vlan+srcmac with XDP") Signed-off-by: Jiayuan Chen Link: https://patch.msgid.link/20260226080306.98766-2-jiayuan.chen@linux.dev Signed-off-by: Paolo Abeni Signed-off-by: Rajani Kantha <681739313@139.com> Signed-off-by: Sasha Levin

bonding: refuse to enslave CAN devices

2026-06-19T11:36:54+00:00

[ Upstream commit 8ba68464e4787b6a7ec938826e16124df20fd23d ] syzbot reported a kernel paging request crash in can_rx_unregister() inside net/can/af_can.c. The crash occurs because a virtual CAN device (vxcan) is being enslaved to a bonding master. During the enslavement process, the bonding driver mutates and modifies the network device states to fit an Ethernet-like aggregation model. However, CAN devices operate on a completely different Layer 2 architecture, relying on the CAN mid-layer private data structure (can_ml_priv) instead of standard Ethernet structures. Since bonding does not initialize or maintain these CAN structures, subsequent operations on the half-enslaved interface (such as closing associated sockets via isotp_release) lead to a null-pointer dereference when accessing the CAN receiver lists. Bonding CAN interfaces is architecturally invalid as CAN lacks MAC addresses, ARP capabilities, and standard Ethernet link-layer mechanisms. While generic loopback devices are blocked globally in net/core/dev.c, virtual CAN devices bypass this check because they do not carry the IFF_LOOPBACK flag, despite acting as local software-loopbacks. Fix this by explicitly blocking network devices of type ARPHRD_CAN from being enslaved at the very beginning of bond_enslave(). This prevents illegal state mutations, eliminates the resulting KASAN crashes, and avoids potential memory leaks from incomplete socket cleanups. As the CAN support has been added a long time after bonding the Fixes-tag points to the introduction of ARPHRD_CAN that would have needed a specific handling in bonding_main.c. Fixes: cd05acfe65ed ("[CAN]: Allocate protocol numbers for PF_CAN") Reported-by: syzbot+8ed98cbd0161632bce95@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=8ed98cbd0161632bce95 Signed-off-by: Oliver Hartkopp Acked-by: Jay Vosburgh Link: https://patch.msgid.link/20260526-bonding-candev-v1-1-ba1df400918a@hartkopp.net Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bonding: update the slave array for broadcast mode

2026-06-01T15:39:31+00:00

[ Upstream commit e0caeb24f538c3c9c94f471882ceeb43d9dc2739 ] This patch fixes ce7a381697cb ("net: bonding: add broadcast_neighbor option for 802.3ad"). Before this commit, on the broadcast mode, all devices were traversed using the bond_for_each_slave_rcu. This patch supports traversing devices by using all_slaves. Therefore, we need to update the slave array when enslave or release slave. Fixes: ce7a381697cb ("net: bonding: add broadcast_neighbor option for 802.3ad") Cc: Simon Horman Cc: Jonathan Corbet Cc: Andrew Lunn Cc: Reported-by: Jiri Slaby Tested-by: Jiri Slaby Link: https://lore.kernel.org/all/a97e6e1e-81bc-4a79-8352-9e4794b0d2ca@kernel.org/ Signed-off-by: Tonghao Zhang Reviewed-by: Hangbin Liu Reviewed-by: Nikolay Aleksandrov Acked-by: Jay Vosburgh Link: https://patch.msgid.link/20251016125136.16568-1-tonghao@bamaicloud.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

bonding: fix NULL pointer dereference in actor_port_prio setting

2026-06-01T15:39:31+00:00

[ Upstream commit 067bf016e99ad72aa4ff869d6dec1fd62a9c6202 ] Liang reported an issue where setting a slave’s actor_port_prio to predefined values such as 0, 255, or 65535 would cause a system crash. The problem occurs because in bond_opt_parse(), when the provided value matches a predefined table entry, the function returns that table entry, which does not contain slave information. Later, in bond_option_actor_port_prio_set(), calling bond_slave_get_rtnl() leads to a NULL pointer dereference. Since actor_port_prio is defined as a u16 and initialized to the default value of 255 in ad_initialize_port(), there is no need for the bond_actor_port_prio_tbl. Using the BOND_OPTFLAG_RAWVAL flag is sufficient. Fixes: 6b6dc81ee7e8 ("bonding: add support for per-port LACP actor priority") Reported-by: Liang Li Signed-off-by: Hangbin Liu Link: https://patch.msgid.link/20251105072620.164841-1-liuhangbin@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin