================================================================== BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick read-write to 0xffff8881000c5ed8 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:5677 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 check_access kernel/kcsan/core.c:787 [inline] __tsan_read8+0x121/0x190 kernel/kcsan/core.c:1025 kmalloc_reserve net/core/skbuff.c:613 [inline] __alloc_skb+0x34c/0x690 net/core/skbuff.c:713 alloc_skb include/linux/skbuff.h:1383 [inline] synproxy_send_client_synack+0xd4/0x5d0 net/netfilter/nf_synproxy_core.c:461 nft_synproxy_eval_v4+0x247/0x2a0 net/netfilter/nft_synproxy.c:60 nft_synproxy_do_eval+0x1cf/0x270 net/netfilter/nft_synproxy.c:142 nft_synproxy_eval+0x29/0x40 net/netfilter/nft_synproxy.c:248 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x1f3/0xd90 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x2f0/0x320 net/netfilter/nft_chain_filter.c:162 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0x78/0x180 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK include/linux/netfilter.h:316 [inline] ip_local_deliver+0x199/0x1e0 net/ipv4/ip_input.c:262 dst_input include/net/dst.h:480 [inline] ip_rcv_finish+0x188/0x1a0 net/ipv4/ip_input.c:492 NF_HOOK include/linux/netfilter.h:318 [inline] ip_rcv+0x62/0x160 net/ipv4/ip_input.c:612 __netif_receive_skb_one_core net/core/dev.c:6209 [inline] __netif_receive_skb net/core/dev.c:6322 [inline] process_backlog+0x341/0x670 net/core/dev.c:6673 __napi_poll+0x61/0x300 net/core/dev.c:7737 napi_poll net/core/dev.c:7800 [inline] net_rx_action+0x452/0x930 net/core/dev.c:7957 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+0x52b/0x630 drivers/net/netdevsim/dev.c:922 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-write to 0xffff8881000c5ed8 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:5677 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 should_watch kernel/kcsan/core.c:280 [inline] check_access kernel/kcsan/core.c:752 [inline] __tsan_unaligned_write2+0x14c/0x180 kernel/kcsan/core.c:1023 __finalize_skb_around net/core/skbuff.c:404 [inline] __alloc_skb+0x483/0x690 net/core/skbuff.c:720 alloc_skb include/linux/skbuff.h:1383 [inline] synproxy_send_client_synack+0xd4/0x5d0 net/netfilter/nf_synproxy_core.c:461 nft_synproxy_eval_v4+0x247/0x2a0 net/netfilter/nft_synproxy.c:60 nft_synproxy_do_eval+0x1cf/0x270 net/netfilter/nft_synproxy.c:142 nft_synproxy_eval+0x29/0x40 net/netfilter/nft_synproxy.c:248 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x1f3/0xd90 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x2f0/0x320 net/netfilter/nft_chain_filter.c:162 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0x78/0x180 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK include/linux/netfilter.h:316 [inline] ip_local_deliver+0x199/0x1e0 net/ipv4/ip_input.c:262 dst_input include/net/dst.h:480 [inline] ip_rcv_finish+0x188/0x1a0 net/ipv4/ip_input.c:492 NF_HOOK include/linux/netfilter.h:318 [inline] ip_rcv+0x62/0x160 net/ipv4/ip_input.c:612 __netif_receive_skb_one_core net/core/dev.c:6209 [inline] __netif_receive_skb net/core/dev.c:6322 [inline] process_backlog+0x341/0x670 net/core/dev.c:6673 __napi_poll+0x61/0x300 net/core/dev.c:7737 napi_poll net/core/dev.c:7800 [inline] net_rx_action+0x452/0x930 net/core/dev.c:7957 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:1383 [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/0x630 drivers/net/netdevsim/dev.c:922 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 value changed: 0x0000000001e73690 -> 0x0000000001e75da0 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 3691 Comm: kworker/u8:21 Tainted: G W syzkaller #0 PREEMPT(full) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Workqueue: events_unbound nsim_dev_trap_report_work ==================================================================