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

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

bridge: Redirect to backup port when port is administratively down

2025-12-06T21:12:19+00:00

[ Upstream commit 3d05b24429e1de7a17c8fdccb04a04dbc8ad297b ] If a backup port is configured for a bridge port, the bridge will redirect known unicast traffic towards the backup port when the primary port is administratively up but without a carrier. This is useful, for example, in MLAG configurations where a system is connected to two switches and there is a peer link between both switches. The peer link serves as the backup port in case one of the switches loses its connection to the multi-homed system. In order to avoid flooding when the primary port loses its carrier, the bridge does not flush dynamic FDB entries pointing to the port upon STP disablement, if the port has a backup port. The above means that known unicast traffic destined to the primary port will be blackholed when the port is put administratively down, until the FDB entries pointing to it are aged-out. Given that the current behavior is quite weird and unlikely to be depended on by anyone, amend the bridge to redirect to the backup port also when the primary port is administratively down and not only when it does not have a carrier. The change is motivated by a report from a user who expected traffic to be redirected to the backup port when the primary port was put administratively down while debugging a network issue. Reviewed-by: Petr Machata Signed-off-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20250812080213.325298-2-idosch@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: bridge: mst: Check vlan state for egress decision

2024-08-03T06:49:09+00:00

[ Upstream commit 0a1868b93fad5938dbcca77286b25bf211c49f7a ] If a port is blocking in the common instance but forwarding in an MST instance, traffic egressing the bridge will be dropped because the state of the common instance is overriding that of the MST instance. Fix this by skipping the port state check in MST mode to allow checking the vlan state via br_allowed_egress(). This is similar to what happens in br_handle_frame_finish() when checking ingress traffic, which was introduced in the change below. Fixes: ec7328b59176 ("net: bridge: mst: Multiple Spanning Tree (MST) mode") Signed-off-by: Elliot Ayrey Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

net: bridge: fix corrupted ethernet header on multicast-to-unicast

2024-05-17T09:56:12+00:00

[ Upstream commit 86b29d830ad69eecff25b22dc96c14c6573718e6 ] The change from skb_copy to pskb_copy unfortunately changed the data copying to omit the ethernet header, since it was pulled before reaching this point. Fix this by calling __skb_push/pull around pskb_copy. Fixes: 59c878cbcdd8 ("net: bridge: fix multicast-to-unicast with fraglist GSO") Signed-off-by: Felix Fietkau Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

net: bridge: fix multicast-to-unicast with fraglist GSO

2024-05-17T09:56:01+00:00

[ Upstream commit 59c878cbcdd80ed39315573b3511d0acfd3501b5 ] Calling skb_copy on a SKB_GSO_FRAGLIST skb is not valid, since it returns an invalid linearized skb. This code only needs to change the ethernet header, so pskb_copy is the right function to call here. Fixes: 6db6f0eae605 ("bridge: multicast to unicast") Signed-off-by: Felix Fietkau Acked-by: Paolo Abeni Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller 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: add vlan_get_protocol_and_depth() helper

2023-05-24T16:32:32+00:00

[ Upstream commit 4063384ef762cc5946fc7a3f89879e76c6ec51e2 ] Before blamed commit, pskb_may_pull() was used instead of skb_header_pointer() in __vlan_get_protocol() and friends. Few callers depended on skb->head being populated with MAC header, syzbot caught one of them (skb_mac_gso_segment()) Add vlan_get_protocol_and_depth() to make the intent clearer and use it where sensible. This is a more generic fix than commit e9d3f80935b6 ("net/af_packet: make sure to pull mac header") which was dealing with a similar issue. kernel BUG at include/linux/skbuff.h:2655 ! invalid opcode: 0000 [#1] SMP KASAN CPU: 0 PID: 1441 Comm: syz-executor199 Not tainted 6.1.24-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023 RIP: 0010:__skb_pull include/linux/skbuff.h:2655 [inline] RIP: 0010:skb_mac_gso_segment+0x68f/0x6a0 net/core/gro.c:136 Code: fd 48 8b 5c 24 10 44 89 6b 70 48 c7 c7 c0 ae 0d 86 44 89 e6 e8 a1 91 d0 00 48 c7 c7 00 af 0d 86 48 89 de 31 d2 e8 d1 4a e9 ff <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 RSP: 0018:ffffc90001bd7520 EFLAGS: 00010286 RAX: ffffffff8469736a RBX: ffff88810f31dac0 RCX: ffff888115a18b00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90001bd75e8 R08: ffffffff84697183 R09: fffff5200037adf9 R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000012 R13: 000000000000fee5 R14: 0000000000005865 R15: 000000000000fed7 FS: 000055555633f300(0000) GS:ffff8881f6a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000000 CR3: 0000000116fea000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: [] __skb_gso_segment+0x32d/0x4c0 net/core/dev.c:3419 [] skb_gso_segment include/linux/netdevice.h:4819 [inline] [] validate_xmit_skb+0x3aa/0xee0 net/core/dev.c:3725 [] __dev_queue_xmit+0x1332/0x3300 net/core/dev.c:4313 [] dev_queue_xmit+0x17/0x20 include/linux/netdevice.h:3029 [] packet_snd net/packet/af_packet.c:3111 [inline] [] packet_sendmsg+0x49d2/0x6470 net/packet/af_packet.c:3142 [] sock_sendmsg_nosec net/socket.c:716 [inline] [] sock_sendmsg net/socket.c:736 [inline] [] __sys_sendto+0x472/0x5f0 net/socket.c:2139 [] __do_sys_sendto net/socket.c:2151 [inline] [] __se_sys_sendto net/socket.c:2147 [inline] [] __x64_sys_sendto+0xe5/0x100 net/socket.c:2147 [] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [] do_syscall_64+0x2f/0x50 arch/x86/entry/common.c:80 [] entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: 469aceddfa3e ("vlan: consolidate VLAN parsing code and limit max parsing depth") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Toke Høiland-Jørgensen Cc: Willem de Bruijn Reviewed-by: Simon Horman Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

net: Add skb_clear_tstamp() to keep the mono delivery_time

2022-03-03T14:38:48+00:00

Right now, skb->tstamp is reset to 0 whenever the skb is forwarded. If skb->tstamp has the mono delivery_time, clearing it can hurt the performance when it finally transmits out to fq@phy-dev. The earlier patch added a skb->mono_delivery_time bit to flag the skb->tstamp carrying the mono delivery_time. This patch adds skb_clear_tstamp() helper which keeps the mono delivery_time and clears everything else. The delivery_time clearing will be postponed until the stack knows the skb will be delivered locally. It will be done in a latter patch. Signed-off-by: Martin KaFai Lau Signed-off-by: David S. Miller

net: bridge: fix build when setting skb->offload_fwd_mark with CONFIG_NET_SWITCHDEV=n

2021-07-24T20:48:26+00:00

Switchdev support can be disabled at compile time, and in that case, struct sk_buff will not contain the offload_fwd_mark field. To make the code in br_forward.c work in both cases, we do what is done in other places and we create a helper function, with an empty shim definition, that is implemented by the br_switchdev.o translation module. This is always compiled if and only if CONFIG_NET_SWITCHDEV is y or m. Reported-by: kernel test robot Fixes: 472111920f1c ("net: bridge: switchdev: allow the TX data plane forwarding to be offloaded") Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: bridge: switchdev: allow the TX data plane forwarding to be offloaded

2021-07-23T15:32:37+00:00

Allow switchdevs to forward frames from the CPU in accordance with the bridge configuration in the same way as is done between bridge ports. This means that the bridge will only send a single skb towards one of the ports under the switchdev's control, and expects the driver to deliver the packet to all eligible ports in its domain. Primarily this improves the performance of multicast flows with multiple subscribers, as it allows the hardware to perform the frame replication. The basic flow between the driver and the bridge is as follows: - When joining a bridge port, the switchdev driver calls switchdev_bridge_port_offload() with tx_fwd_offload = true. - The bridge sends offloadable skbs to one of the ports under the switchdev's control using skb->offload_fwd_mark = true. - The switchdev driver checks the skb->offload_fwd_mark field and lets its FDB lookup select the destination port mask for this packet. v1->v2: - convert br_input_skb_cb::fwd_hwdoms to a plain unsigned long - introduce a static key "br_switchdev_fwd_offload_used" to minimize the impact of the newly introduced feature on all the setups which don't have hardware that can make use of it - introduce a check for nbp->flags & BR_FWD_OFFLOAD to optimize cache line access - reorder nbp_switchdev_frame_mark_accel() and br_handle_vlan() in __br_forward() - do not strip VLAN on egress if forwarding offload on VLAN-aware bridge is being used - propagate errors from .ndo_dfwd_add_station() if not EOPNOTSUPP v2->v3: - replace the solution based on .ndo_dfwd_add_station with a solution based on switchdev_bridge_port_offload - rename BR_FWD_OFFLOAD to BR_TX_FWD_OFFLOAD v3->v4: rebase v4->v5: - make sure the static key is decremented on bridge port unoffload - more function and variable renaming and comments for them: br_switchdev_fwd_offload_used to br_switchdev_tx_fwd_offload br_switchdev_accels_skb to br_switchdev_frame_uses_tx_fwd_offload nbp_switchdev_frame_mark_tx_fwd to nbp_switchdev_frame_mark_tx_fwd_to_hwdom nbp_switchdev_frame_mark_accel to nbp_switchdev_frame_mark_tx_fwd_offload fwd_accel to tx_fwd_offload Signed-off-by: Tobias Waldekranz Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller