kernel/linux.git/drivers/net/bonding, branch v6.12.98

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

2026-07-24T14:10:58+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

bonding: fix xfrm offload feature setup on active-backup mode

2026-07-18T14:51:55+00:00

[ Upstream commit 5b66169f6be4847008c0aea50885ff0632151479 ] The active-backup bonding mode supports XFRM ESP offload. However, when a bond is added using command like `ip link add bond0 type bond mode 1 miimon 100`, the `ethtool -k` command shows that the XFRM ESP offload is disabled. This occurs because, in bond_newlink(), we change bond link first and register bond device later. So the XFRM feature update in bond_option_mode_set() is not called as the bond device is not yet registered, leading to the offload feature not being set successfully. To resolve this issue, we can modify the code order in bond_newlink() to ensure that the bond device is registered first before changing the bond link parameters. This change will allow the XFRM ESP offload feature to be correctly enabled. Fixes: 007ab5345545 ("bonding: fix feature flag setting at init time") Signed-off-by: Hangbin Liu Link: https://patch.msgid.link/20250925023304.472186-1-liuhangbin@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

bonding: do not set usable_slaves for broadcast mode

2026-07-04T11:43:36+00:00

commit 45fc134bcfadde456639c1b1e206e6918d69a553 upstream. After commit e0caeb24f538 ("net: bonding: update the slave array for broadcast mode"), broadcast mode will also set all_slaves and usable_slaves during bond_enslave(). But if we also set updelay, during enslave, the slave init state will be BOND_LINK_BACK. And later bond_update_slave_arr() will alloc usable_slaves but add nothing. This will cause bond_miimon_inspect() to have ignore_updelay always true. So the updelay will be always ignored. e.g. [ 6.498368] bond0: (slave veth2): link status definitely down, disabling slave [ 7.536371] bond0: (slave veth2): link status up, enabling it in 0 ms [ 7.536402] bond0: (slave veth2): link status definitely up, 10000 Mbps full duplex To fix it, we can either always call bond_update_slave_arr() on every place when link changes. Or, let's just not set usable_slaves for broadcast mode. Fixes: e0caeb24f538 ("net: bonding: update the slave array for broadcast mode") Reported-by: Liang Li Signed-off-by: Hangbin Liu Link: https://patch.msgid.link/20260304-b4-bond_updelay-v1-1-f72eb2e454d0@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

bonding: annotate data-races arcound churn variables

2026-07-04T11:43:36+00:00

commit b47ff80f280e18ad2310f44293cc057d9b64ff11 upstream. These fields are updated asynchronously by the bonding state machine in ad_churn_machine() while holding bond->mode_lock. bond_info_show_slave() and bond_fill_slave_info() read them without bond->mode_lock being held, we need to add READ_ONCE() and WRITE_ONCE() annotations. Note that AD_CHURN_MONITOR, AD_CHURN, and AD_NO_CHURN are defined exclusively in (kernel private) include/net/bond_3ad.h header. They should be moved to include/uapi/linux/if_bonding.h or userspace tools will have to hardcode their values. Fixes: 4916f2e2f3fc ("bonding: print churn state via netlink") Fixes: 14c9551a32eb ("bonding: Implement port churn-machine (AD standard 43.4.17).") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260603123514.388226-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net: bonding: update the slave array for broadcast mode

2026-07-04T11:43:36+00:00

commit e0caeb24f538c3c9c94f471882ceeb43d9dc2739 upstream. 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: Greg Kroah-Hartman

bonding: fix NULL pointer dereference in actor_port_prio setting

2026-07-04T11:43:26+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: Kevin Berry Signed-off-by: Greg Kroah-Hartman

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

2026-07-04T11:43:26+00:00

[ Upstream commit 2884bf72fb8f03409e423397319205de48adca16 ] 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: Kevin Berry Signed-off-by: Greg Kroah-Hartman

bonding: 3ad: implement proper RCU rules for port->aggregator

2026-07-04T11:43:26+00:00

[ Upstream commit c4f050ce06c56cfb5993268af4a5cb66ed1cd04e ] syzbot found a data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler [1] which hints at lack of proper RCU implementation. Add __rcu qualifier to port->aggregator, and add proper RCU API. [1] BUG: KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler write to 0xffff88813cf5c4b0 of 8 bytes by task 36 on cpu 0: ad_port_selection_logic drivers/net/bonding/bond_3ad.c:1659 [inline] bond_3ad_state_machine_handler+0x9d5/0x2d60 drivers/net/bonding/bond_3ad.c:2569 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3385 worker_thread+0x58a/0x780 kernel/workqueue.c:3466 kthread+0x22a/0x280 kernel/kthread.c:436 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 read to 0xffff88813cf5c4b0 of 8 bytes by task 22063 on cpu 1: __bond_3ad_get_active_agg_info drivers/net/bonding/bond_3ad.c:2858 [inline] bond_3ad_get_active_agg_info+0x8c/0x230 drivers/net/bonding/bond_3ad.c:2881 bond_fill_info+0xe0f/0x10f0 drivers/net/bonding/bond_netlink.c:853 rtnl_link_info_fill net/core/rtnetlink.c:906 [inline] rtnl_link_fill+0x1d7/0x4e0 net/core/rtnetlink.c:927 rtnl_fill_ifinfo+0xf8e/0x1380 net/core/rtnetlink.c:2168 rtmsg_ifinfo_build_skb+0x11c/0x1b0 net/core/rtnetlink.c:4453 rtmsg_ifinfo_event net/core/rtnetlink.c:4486 [inline] rtmsg_ifinfo+0x6d/0x110 net/core/rtnetlink.c:4495 __dev_notify_flags+0x76/0x390 net/core/dev.c:9790 netif_change_flags+0xac/0xd0 net/core/dev.c:9823 do_setlink+0x905/0x2950 net/core/rtnetlink.c:3180 rtnl_group_changelink net/core/rtnetlink.c:3813 [inline] __rtnl_newlink net/core/rtnetlink.c:3981 [inline] rtnl_newlink+0xf55/0x1400 net/core/rtnetlink.c:4109 rtnetlink_rcv_msg+0x64b/0x720 net/core/rtnetlink.c:6995 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:7022 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x5a8/0x680 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x563/0x5b0 net/socket.c:2698 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2752 __sys_sendmsg net/socket.c:2784 [inline] __do_sys_sendmsg net/socket.c:2789 [inline] __se_sys_sendmsg net/socket.c:2787 [inline] __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2787 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x0000000000000000 -> 0xffff88813cf5c400 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 22063 Comm: syz.0.31122 Tainted: G W syzkaller #0 PREEMPT(full) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Fixes: 47e91f56008b ("bonding: use RCU protection for 3ad xmit path") Reported-by: syzbot+9bb2ff2a4ab9e17307e1@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/69f0a82f.050a0220.3aadc4.0000.GAE@google.com/ Signed-off-by: Eric Dumazet Cc: Jay Vosburgh Cc: Andrew Lunn Link: https://patch.msgid.link/20260428123207.3809211-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Kevin Berry Signed-off-by: Greg Kroah-Hartman

bonding: print churn state via netlink

2026-07-04T11:43:26+00:00

[ Upstream commit 4916f2e2f3fc9aef289fcd07949301e5c29094c2 ] Currently, the churn state is printed only in sysfs. Add netlink support so users could get the state via netlink. Signed-off-by: Hangbin Liu Link: https://patch.msgid.link/20260224020215.6012-1-liuhangbin@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Kevin Berry Signed-off-by: Greg Kroah-Hartman

bonding: add support for per-port LACP actor priority

2026-07-04T11:43:26+00:00

[ Upstream commit 6b6dc81ee7e8ca87c71a533e1d69cf96a4f1e986 ] Introduce a new netlink attribute 'actor_port_prio' to allow setting the LACP actor port priority on a per-slave basis. This extends the existing bonding infrastructure to support more granular control over LACP negotiations. The priority value is embedded in LACPDU packets and will be used by subsequent patches to influence aggregator selection policies. Signed-off-by: Hangbin Liu Link: https://patch.msgid.link/20250902064501.360822-2-liuhangbin@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Kevin Berry Signed-off-by: Greg Kroah-Hartman