kernel/linux.git/net/bridge/br_input.c, branch v6.1.168

net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled

2026-03-25T10:03:02+00:00

[ Upstream commit e5e890630533bdc15b26a34bb8e7ef539bdf1322 ] When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. Then, if neigh_suppress is enabled and an ICMPv6 Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will dereference ipv6_stub->nd_tbl which is NULL, passing it to neigh_lookup(). This causes a kernel NULL pointer dereference. BUG: kernel NULL pointer dereference, address: 0000000000000268 Oops: 0000 [#1] PREEMPT SMP NOPTI [...] RIP: 0010:neigh_lookup+0x16/0xe0 [...] Call Trace: ? neigh_lookup+0x16/0xe0 br_do_suppress_nd+0x160/0x290 [bridge] br_handle_frame_finish+0x500/0x620 [bridge] br_handle_frame+0x353/0x440 [bridge] __netif_receive_skb_core.constprop.0+0x298/0x1110 __netif_receive_skb_one_core+0x3d/0xa0 process_backlog+0xa0/0x140 __napi_poll+0x2c/0x170 net_rx_action+0x2c4/0x3a0 handle_softirqs+0xd0/0x270 do_softirq+0x3f/0x60 Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in the callers. This is in essence disabling NS/NA suppression when IPv6 is disabled. Fixes: ed842faeb2bd ("bridge: suppress nd pkts on BR_NEIGH_SUPPRESS ports") Reported-by: Guruprasad C P Closes: https://lore.kernel.org/netdev/CAHXs0ORzd62QOG-Fttqa2Cx_A_VFp=utE2H2VTX5nqfgs7LDxQ@mail.gmail.com/ Signed-off-by: Fernando Fernandez Mancera Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260304120357.9778-1-fmancera@suse.de Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bridge: fix static key check

2026-02-06T15:44:16+00:00

[ Upstream commit cc0cf10fdaeadf5542d64a55b5b4120d3df90b7d ] Fix the check if netfilter's static keys are available. netfilter defines and exports static keys if CONFIG_JUMP_LABEL is enabled. (HAVE_JUMP_LABEL is never defined.) Fixes: 971502d77faa ("bridge: netfilter: unroll NF_HOOK helper in bridge input path") Signed-off-by: Martin Kaiser Reviewed-by: Florian Westphal Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260127101925.1754425-1-martin@kaiser.cx Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bridge: fix use-after-free due to MST port state bypass

2025-12-06T21:12:30+00:00

[ Upstream commit 8dca36978aa80bab9d4da130c211db75c9e00048 ] syzbot reported[1] a use-after-free when deleting an expired fdb. It is due to a race condition between learning still happening and a port being deleted, after all its fdbs have been flushed. The port's state has been toggled to disabled so no learning should happen at that time, but if we have MST enabled, it will bypass the port's state, that together with VLAN filtering disabled can lead to fdb learning at a time when it shouldn't happen while the port is being deleted. VLAN filtering must be disabled because we flush the port VLANs when it's being deleted which will stop learning. This fix adds a check for the port's vlan group which is initialized to NULL when the port is getting deleted, that avoids the port state bypass. When MST is enabled there would be a minimal new overhead in the fast-path because the port's vlan group pointer is cache-hot. [1] https://syzkaller.appspot.com/bug?extid=dd280197f0f7ab3917be Fixes: ec7328b59176 ("net: bridge: mst: Multiple Spanning Tree (MST) mode") Reported-by: syzbot+dd280197f0f7ab3917be@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/69088ffa.050a0220.29fc44.003d.GAE@google.com/ Signed-off-by: Nikolay Aleksandrov Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20251105111919.1499702-2-razor@blackwall.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

netfilter: br_netfilter: skip conntrack input hook for promisc packets

2024-04-27T15:07:07+00:00

[ Upstream commit 751de2012eafa4d46d8081056761fa0e9cc8a178 ] For historical reasons, when bridge device is in promisc mode, packets that are directed to the taps follow bridge input hook path. This patch adds a workaround to reset conntrack for these packets. Jianbo Liu reports warning splats in their test infrastructure where cloned packets reach the br_netfilter input hook to confirm the conntrack object. Scratch one bit from BR_INPUT_SKB_CB to annotate that this packet has reached the input hook because it is passed up to the bridge device to reach the taps. [ 57.571874] WARNING: CPU: 1 PID: 0 at net/bridge/br_netfilter_hooks.c:616 br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.572749] Modules linked in: xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat xt_addrtype xt_conntrack nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry overlay rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_isc si ib_umad rdma_cm ib_ipoib iw_cm ib_cm mlx5_ib ib_uverbs ib_core mlx5ctl mlx5_core [ 57.575158] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.8.0+ #19 [ 57.575700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 57.576662] RIP: 0010:br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.577195] Code: fe ff ff 41 bd 04 00 00 00 be 04 00 00 00 e9 4a ff ff ff be 04 00 00 00 48 89 ef e8 f3 a9 3c e1 66 83 ad b4 00 00 00 04 eb 91 <0f> 0b e9 f1 fe ff ff 0f 0b e9 df fe ff ff 48 89 df e8 b3 53 47 e1 [ 57.578722] RSP: 0018:ffff88885f845a08 EFLAGS: 00010202 [ 57.579207] RAX: 0000000000000002 RBX: ffff88812dfe8000 RCX: 0000000000000000 [ 57.579830] RDX: ffff88885f845a60 RSI: ffff8881022dc300 RDI: 0000000000000000 [ 57.580454] RBP: ffff88885f845a60 R08: 0000000000000001 R09: 0000000000000003 [ 57.581076] R10: 00000000ffff1300 R11: 0000000000000002 R12: 0000000000000000 [ 57.581695] R13: ffff8881047ffe00 R14: ffff888108dbee00 R15: ffff88814519b800 [ 57.582313] FS: 0000000000000000(0000) GS:ffff88885f840000(0000) knlGS:0000000000000000 [ 57.583040] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 57.583564] CR2: 000000c4206aa000 CR3: 0000000103847001 CR4: 0000000000370eb0 [ 57.584194] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 57.584820] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 57.585440] Call Trace: [ 57.585721] [ 57.585976] ? __warn+0x7d/0x130 [ 57.586323] ? br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.586811] ? report_bug+0xf1/0x1c0 [ 57.587177] ? handle_bug+0x3f/0x70 [ 57.587539] ? exc_invalid_op+0x13/0x60 [ 57.587929] ? asm_exc_invalid_op+0x16/0x20 [ 57.588336] ? br_nf_local_in+0x157/0x180 [br_netfilter] [ 57.588825] nf_hook_slow+0x3d/0xd0 [ 57.589188] ? br_handle_vlan+0x4b/0x110 [ 57.589579] br_pass_frame_up+0xfc/0x150 [ 57.589970] ? br_port_flags_change+0x40/0x40 [ 57.590396] br_handle_frame_finish+0x346/0x5e0 [ 57.590837] ? ipt_do_table+0x32e/0x430 [ 57.591221] ? br_handle_local_finish+0x20/0x20 [ 57.591656] br_nf_hook_thresh+0x4b/0xf0 [br_netfilter] [ 57.592286] ? br_handle_local_finish+0x20/0x20 [ 57.592802] br_nf_pre_routing_finish+0x178/0x480 [br_netfilter] [ 57.593348] ? br_handle_local_finish+0x20/0x20 [ 57.593782] ? nf_nat_ipv4_pre_routing+0x25/0x60 [nf_nat] [ 57.594279] br_nf_pre_routing+0x24c/0x550 [br_netfilter] [ 57.594780] ? br_nf_hook_thresh+0xf0/0xf0 [br_netfilter] [ 57.595280] br_handle_frame+0x1f3/0x3d0 [ 57.595676] ? br_handle_local_finish+0x20/0x20 [ 57.596118] ? br_handle_frame_finish+0x5e0/0x5e0 [ 57.596566] __netif_receive_skb_core+0x25b/0xfc0 [ 57.597017] ? __napi_build_skb+0x37/0x40 [ 57.597418] __netif_receive_skb_list_core+0xfb/0x220 Fixes: 62e7151ae3eb ("netfilter: bridge: confirm multicast packets before passing them up the stack") Reported-by: Jianbo Liu Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

net: bridge: use DEV_STATS_INC()

2023-10-06T12:56:41+00:00

[ Upstream commit 44bdb313da57322c9b3c108eb66981c6ec6509f4 ] syzbot/KCSAN reported data-races in br_handle_frame_finish() [1] This function can run from multiple cpus without mutual exclusion. Adopt SMP safe DEV_STATS_INC() to update dev->stats fields. Handles updates to dev->stats.tx_dropped while we are at it. [1] BUG: KCSAN: data-race in br_handle_frame_finish / br_handle_frame_finish read-write to 0xffff8881374b2178 of 8 bytes by interrupt on cpu 1: br_handle_frame_finish+0xd4f/0xef0 net/bridge/br_input.c:189 br_nf_hook_thresh+0x1ed/0x220 br_nf_pre_routing_finish_ipv6+0x50f/0x540 NF_HOOK include/linux/netfilter.h:304 [inline] br_nf_pre_routing_ipv6+0x1e3/0x2a0 net/bridge/br_netfilter_ipv6.c:178 br_nf_pre_routing+0x526/0xba0 net/bridge/br_netfilter_hooks.c:508 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline] nf_hook_bridge_pre net/bridge/br_input.c:272 [inline] br_handle_frame+0x4c9/0x940 net/bridge/br_input.c:417 __netif_receive_skb_core+0xa8a/0x21e0 net/core/dev.c:5417 __netif_receive_skb_one_core net/core/dev.c:5521 [inline] __netif_receive_skb+0x57/0x1b0 net/core/dev.c:5637 process_backlog+0x21f/0x380 net/core/dev.c:5965 __napi_poll+0x60/0x3b0 net/core/dev.c:6527 napi_poll net/core/dev.c:6594 [inline] net_rx_action+0x32b/0x750 net/core/dev.c:6727 __do_softirq+0xc1/0x265 kernel/softirq.c:553 run_ksoftirqd+0x17/0x20 kernel/softirq.c:921 smpboot_thread_fn+0x30a/0x4a0 kernel/smpboot.c:164 kthread+0x1d7/0x210 kernel/kthread.c:388 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 read-write to 0xffff8881374b2178 of 8 bytes by interrupt on cpu 0: br_handle_frame_finish+0xd4f/0xef0 net/bridge/br_input.c:189 br_nf_hook_thresh+0x1ed/0x220 br_nf_pre_routing_finish_ipv6+0x50f/0x540 NF_HOOK include/linux/netfilter.h:304 [inline] br_nf_pre_routing_ipv6+0x1e3/0x2a0 net/bridge/br_netfilter_ipv6.c:178 br_nf_pre_routing+0x526/0xba0 net/bridge/br_netfilter_hooks.c:508 nf_hook_entry_hookfn include/linux/netfilter.h:144 [inline] nf_hook_bridge_pre net/bridge/br_input.c:272 [inline] br_handle_frame+0x4c9/0x940 net/bridge/br_input.c:417 __netif_receive_skb_core+0xa8a/0x21e0 net/core/dev.c:5417 __netif_receive_skb_one_core net/core/dev.c:5521 [inline] __netif_receive_skb+0x57/0x1b0 net/core/dev.c:5637 process_backlog+0x21f/0x380 net/core/dev.c:5965 __napi_poll+0x60/0x3b0 net/core/dev.c:6527 napi_poll net/core/dev.c:6594 [inline] net_rx_action+0x32b/0x750 net/core/dev.c:6727 __do_softirq+0xc1/0x265 kernel/softirq.c:553 do_softirq+0x5e/0x90 kernel/softirq.c:454 __local_bh_enable_ip+0x64/0x70 kernel/softirq.c:381 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline] _raw_spin_unlock_bh+0x36/0x40 kernel/locking/spinlock.c:210 spin_unlock_bh include/linux/spinlock.h:396 [inline] batadv_tt_local_purge+0x1a8/0x1f0 net/batman-adv/translation-table.c:1356 batadv_tt_purge+0x2b/0x630 net/batman-adv/translation-table.c:3560 process_one_work kernel/workqueue.c:2630 [inline] process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703 worker_thread+0x525/0x730 kernel/workqueue.c:2784 kthread+0x1d7/0x210 kernel/kthread.c:388 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 value changed: 0x00000000000d7190 -> 0x00000000000d7191 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 14848 Comm: kworker/u4:11 Not tainted 6.6.0-rc1-syzkaller-00236-gad8a69f361b9 #0 Fixes: 1c29fc4989bc ("[BRIDGE]: keep track of received multicast packets") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Roopa Prabhu Cc: Nikolay Aleksandrov Cc: bridge@lists.linux-foundation.org Acked-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20230918091351.1356153-1-edumazet@google.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net: bridge: Clear offload_fwd_mark when passing frame up bridge interface.

2022-05-19T07:20:44+00:00

It is possible to stack bridges on top of each other. Consider the following which makes use of an Ethernet switch: br1 / \ / \ / \ br0.11 wlan0 | br0 / | \ p1 p2 p3 br0 is offloaded to the switch. Above br0 is a vlan interface, for vlan 11. This vlan interface is then a slave of br1. br1 also has a wireless interface as a slave. This setup trunks wireless lan traffic over the copper network inside a VLAN. A frame received on p1 which is passed up to the bridge has the skb->offload_fwd_mark flag set to true, indicating that the switch has dealt with forwarding the frame out ports p2 and p3 as needed. This flag instructs the software bridge it does not need to pass the frame back down again. However, the flag is not getting reset when the frame is passed upwards. As a result br1 sees the flag, wrongly interprets it, and fails to forward the frame to wlan0. When passing a frame upwards, clear the flag. This is the Rx equivalent of br_switchdev_frame_unmark() in br_dev_xmit(). Fixes: f1c2eddf4cb6 ("bridge: switchdev: Use an helper to clear forward mark") Signed-off-by: Andrew Lunn Reviewed-by: Ido Schimmel Tested-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20220518005840.771575-1-andrew@lunn.ch Signed-off-by: Paolo Abeni

net: bridge: mst: Multiple Spanning Tree (MST) mode

2022-03-17T23:49:57+00:00

Allow the user to switch from the current per-VLAN STP mode to an MST mode. Up to this point, per-VLAN STP states where always isolated from each other. This is in contrast to the MSTP standard (802.1Q-2018, Clause 13.5), where VLANs are grouped into MST instances (MSTIs), and the state is managed on a per-MSTI level, rather that at the per-VLAN level. Perhaps due to the prevalence of the standard, many switching ASICs are built after the same model. Therefore, add a corresponding MST mode to the bridge, which we can later add offloading support for in a straight-forward way. For now, all VLANs are fixed to MSTI 0, also called the Common Spanning Tree (CST). That is, all VLANs will follow the port-global state. Upcoming changes will make this actually useful by allowing VLANs to be mapped to arbitrary MSTIs and allow individual MSTI states to be changed. Signed-off-by: Tobias Waldekranz Acked-by: Nikolay Aleksandrov Signed-off-by: Jakub Kicinski

net: bridge: Add support for bridge port in locked mode

2022-02-23T12:52:34+00:00

In a 802.1X scenario, clients connected to a bridge port shall not be allowed to have traffic forwarded until fully authenticated. A static fdb entry of the clients MAC address for the bridge port unlocks the client and allows bidirectional communication. This scenario is facilitated with setting the bridge port in locked mode, which is also supported by various switchcore chipsets. Signed-off-by: Hans Schultz Acked-by: Nikolay Aleksandrov Reviewed-by: Ido Schimmel Signed-off-by: David S. Miller

net: bridge: change return type of br_handle_ingress_vlan_tunnel

2021-08-24T23:51:09+00:00

br_handle_ingress_vlan_tunnel() is only referenced in br_handle_frame(). If br_handle_ingress_vlan_tunnel() is called and return non-zero value, goto drop in br_handle_frame(). But, br_handle_ingress_vlan_tunnel() always return 0. So, the routines that check the return value and goto drop has no meaning. Therefore, change return type of br_handle_ingress_vlan_tunnel() to void and remove if statement of br_handle_frame(). Signed-off-by: Kangmin Park Acked-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20210823102118.17966-1-l4stpr0gr4m@gmail.com Signed-off-by: Jakub Kicinski

net: bridge: add vlan mcast snooping knob

2021-07-20T12:41:20+00:00

Add a global knob that controls if vlan multicast snooping is enabled. The proper contexts (vlan or bridge-wide) will be chosen based on the knob when processing packets and changing bridge device state. Note that vlans have their individual mcast snooping enabled by default, but this knob is needed to turn on bridge vlan snooping. It is disabled by default. To enable the knob vlan filtering must also be enabled, it doesn't make sense to have vlan mcast snooping without vlan filtering since that would lead to inconsistencies. Disabling vlan filtering will also automatically disable vlan mcast snooping. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller