kernel/linux.git/net/bridge/br_input.c, branch v7.2-rc1

net: bridge: use atomic ops to read/change p->flags (II)

2026-06-13T01:03:46+00:00

Use READ_ONCE(p->flags) in br_port_flag_is_set() to keep its ABI. Use test_bit(), clear_bit(), set_bit() in: net/bridge/br_input.c net/bridge/br_mrp.c net/bridge/br_mrp_netlink.c Signed-off-by: Eric Dumazet Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260611203453.3067462-5-edumazet@google.com Signed-off-by: Jakub Kicinski

bridge: Add missing READ_ONCE() annotations around FDB destination port

2026-05-20T01:13:01+00:00

When roaming, the FDB destination port can change without holding the bridge's hash lock. Therefore, add missing READ_ONCE() annotations in both RCU readers and readers that hold the lock. In the latter case, the annotation is not needed in places where the FDB entry was already validated to be a local entry since such entries cannot roam. Acked-by: Nikolay Aleksandrov Signed-off-by: Ido Schimmel Link: https://patch.msgid.link/20260517115009.175163-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski

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

2026-03-05T15:52:56+00:00

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

net: bridge: fix static key check

2026-01-29T03:34:01+00:00

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

net: bridge: annotate data-races around fdb->{updated,used}

2026-01-10T01:36:21+00:00

fdb->updated and fdb->used are read and written locklessly. Add READ_ONCE()/WRITE_ONCE() annotations. Fixes: 31cbc39b6344 ("net: bridge: add option to allow activity notifications for any fdb entries") Reported-by: syzbot+bfab43087ad57222ce96@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/695e3d74.050a0220.1c677c.035f.GAE@google.com/ Signed-off-by: Eric Dumazet Acked-by: Nikolay Aleksandrov Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260108093806.834459-1-edumazet@google.com Signed-off-by: Jakub Kicinski

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

2025-11-06T15:32:17+00:00

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

net: bridge: BROPT_FDB_LOCAL_VLAN_0: Look up FDB on VLAN 0 on miss

2025-09-12T02:02:50+00:00

When BROPT_FDB_LOCAL_VLAN_0 is enabled, the local FDB entries for the member ports as well as the bridge itself should not be created per-VLAN, but instead only on VLAN 0. That means that br_handle_frame_finish() needs to make two lookups: the primary lookup on an appropriate VLAN, and when that misses, a lookup on VLAN 0. Have the second lookup only accept local MAC addresses. Turning this into a generic second-lookup feature is not the goal. Reviewed-by: Ido Schimmel Signed-off-by: Petr Machata Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/8087475009dce360fb68d873b1ed9c80827da302.1757004393.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski

net: bridge: locally receive all multicast packets if IFF_ALLMULTI is set

2025-04-16T00:25:52+00:00

If multicast snooping is enabled, multicast packets may not always end up on the local bridge interface, if the host is not a member of the multicast group. Similar to how IFF_PROMISC allows all packets to be received locally, let IFF_ALLMULTI allow all multicast packets to be received. OpenWrt uses a user space daemon for DHCPv6/RA/NDP handling, and in relay mode it sets the ALLMULTI flag in order to receive all relevant queries on the network. This works for normal network interfaces and non-snooping bridges, but not snooping bridges (unless multicast routing is enabled). Reported-by: Felix Fietkau Closes: https://github.com/openwrt/openwrt/issues/15857#issuecomment-2662851243 Signed-off-by: Shengyu Qu Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/OSZPR01MB8434308370ACAFA90A22980798B32@OSZPR01MB8434.jpnprd01.prod.outlook.com Signed-off-by: Jakub Kicinski

net: bridge: add skb drop reasons to the most common drop points

2024-12-23T18:11:04+00:00

The bridge input code may drop frames for various reasons and at various points in the ingress handling logic. Currently kfree_skb() is used everywhere, and therefore no drop reason is specified. Add drop reasons to the most common drop points. Drop reasons are not added exhaustively to the entire bridge code. The intention is to incrementally add drop reasons to the rest of the bridge code in follow up patches. Signed-off-by: Radu Rendec Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20241219163606.717758-3-rrendec@redhat.com Signed-off-by: Jakub Kicinski

netfilter: br_netfilter: skip conntrack input hook for promisc packets

2024-04-11T10:09:33+00:00

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