syzbot

bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
==================================================================
BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick

read-write to 0xffff8881000c5cd8 of 8 bytes by interrupt on cpu 1:
 wq_worker_tick+0x64/0x240 kernel/workqueue.c:1508
 sched_tick+0xbc/0x1f0 kernel/sched/core.c:5678
 update_process_times+0x15e/0x190 kernel/time/timer.c:2480
 tick_sched_handle kernel/time/tick-sched.c:298 [inline]
 tick_nohz_handler+0x275/0x3d0 kernel/time/tick-sched.c:319
 __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
 __hrtimer_run_queues+0x276/0x4f0 kernel/time/hrtimer.c:1994
 hrtimer_interrupt+0x261/0x850 kernel/time/hrtimer.c:2113
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1061
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 decode_watchpoint kernel/kcsan/encoding.h:74 [inline]
 find_watchpoint kernel/kcsan/core.c:132 [inline]
 check_access kernel/kcsan/core.c:737 [inline]
 __tsan_read8+0x42/0x190 kernel/kcsan/core.c:1025
 hold_time net/bridge/br_fdb.c:65 [inline]
 br_fdb_update+0x76/0x460 net/bridge/br_fdb.c:978
 br_handle_frame_finish+0x337/0x1080 net/bridge/br_input.c:144
 br_nf_hook_thresh+0x233/0x270 net/bridge/br_netfilter_hooks.c:-1
 br_nf_pre_routing_finish_ipv6+0x51d/0x540 net/bridge/br_netfilter_ipv6.c:-1
 NF_HOOK include/linux/netfilter.h:318 [inline]
 br_nf_pre_routing_ipv6+0x1fa/0x2e0 net/bridge/br_netfilter_ipv6.c:183
 br_nf_pre_routing+0x56a/0xbe0 net/bridge/br_netfilter_hooks.c:513
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:291 [inline]
 br_handle_frame+0x85f/0xa60 net/bridge/br_input.c:442
 __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6089
 __netif_receive_skb_one_core net/core/dev.c:6200 [inline]
 __netif_receive_skb net/core/dev.c:6315 [inline]
 process_backlog+0x25b/0x670 net/core/dev.c:6666
 __napi_poll+0x61/0x300 net/core/dev.c:7733
 napi_poll net/core/dev.c:7796 [inline]
 net_rx_action+0x452/0x930 net/core/dev.c:7953
 handle_softirqs+0xb9/0x280 kernel/softirq.c:622
 do_softirq+0x45/0x60 kernel/softirq.c:523
 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:450
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 __alloc_skb+0x658/0x690 net/core/skbuff.c:697
 alloc_skb include/linux/skbuff.h:1385 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline]
 nsim_dev_trap_report_work+0x18a/0x640 drivers/net/netdevsim/dev.c:922
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 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-write to 0xffff8881000c5cd8 of 8 bytes by interrupt on cpu 0:
 wq_worker_tick+0x64/0x240 kernel/workqueue.c:1508
 sched_tick+0xbc/0x1f0 kernel/sched/core.c:5678
 update_process_times+0x15e/0x190 kernel/time/timer.c:2480
 tick_sched_handle kernel/time/tick-sched.c:298 [inline]
 tick_nohz_handler+0x275/0x3d0 kernel/time/tick-sched.c:319
 __run_hrtimer kernel/time/hrtimer.c:1930 [inline]
 __hrtimer_run_queues+0x276/0x4f0 kernel/time/hrtimer.c:1994
 hrtimer_interrupt+0x261/0x850 kernel/time/hrtimer.c:2113
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1061
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 __find_rr_leaf+0x1e0/0x500 net/ipv6/route.c:836
 find_rr_leaf net/ipv6/route.c:892 [inline]
 rt6_select net/ipv6/route.c:936 [inline]
 fib6_table_lookup+0x1db/0x610 net/ipv6/route.c:2254
 ip6_pol_route+0xbf/0xeb0 net/ipv6/route.c:2290
 ip6_pol_route_input+0x42/0x60 net/ipv6/route.c:2347
 pol_lookup_func include/net/ip6_fib.h:667 [inline]
 fib6_rule_lookup+0x366/0x4c0 net/ipv6/fib6_rules.c:123
 ip6_route_input_lookup net/ipv6/route.c:2359 [inline]
 ip6_route_input+0x512/0x620 net/ipv6/route.c:2662
 ip6_rcv_finish_core net/ipv6/ip6_input.c:106 [inline]
 ip6_rcv_finish+0x1be/0x330 net/ipv6/ip6_input.c:117
 NF_HOOK include/linux/netfilter.h:318 [inline]
 ipv6_rcv+0x72/0x170 net/ipv6/ip6_input.c:351
 __netif_receive_skb_one_core net/core/dev.c:6202 [inline]
 __netif_receive_skb net/core/dev.c:6315 [inline]
 netif_receive_skb_internal net/core/dev.c:6401 [inline]
 netif_receive_skb+0xc5/0x4c0 net/core/dev.c:6460
 br_netif_receive_skb net/bridge/br_input.c:30 [inline]
 NF_HOOK include/linux/netfilter.h:318 [inline]
 br_pass_frame_up+0x23b/0x330 net/bridge/br_input.c:70
 br_handle_frame_finish+0xe23/0x1080 net/bridge/br_input.c:-1
 nf_hook_bridge_pre net/bridge/br_input.c:313 [inline]
 br_handle_frame+0x452/0xa60 net/bridge/br_input.c:442
 __netif_receive_skb_core+0x5b1/0x1950 net/core/dev.c:6089
 __netif_receive_skb_one_core net/core/dev.c:6200 [inline]
 __netif_receive_skb net/core/dev.c:6315 [inline]
 process_backlog+0x25b/0x670 net/core/dev.c:6666
 __napi_poll+0x61/0x300 net/core/dev.c:7733
 napi_poll net/core/dev.c:7796 [inline]
 net_rx_action+0x452/0x930 net/core/dev.c:7953
 handle_softirqs+0xb9/0x280 kernel/softirq.c:622
 do_softirq+0x45/0x60 kernel/softirq.c:523
 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:450
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:196 [inline]
 _raw_spin_unlock_bh+0x18/0x20 kernel/locking/spinlock.c:214
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:891 [inline]
 nsim_dev_trap_report_work+0x53b/0x640 drivers/net/netdevsim/dev.c:922
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 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

value changed: 0x00000000019741d0 -> 0x00000000019768e0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4109 Comm: kworker/u8:25 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: events_unbound nsim_dev_trap_report_work
==================================================================
net_ratelimit: 107840 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 122464 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)