================================================================== BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick 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:5804 update_process_times+0x15e/0x190 kernel/time/timer.c:2480 tick_sched_handle kernel/time/tick-sched.c:296 [inline] tick_nohz_handler+0x227/0x380 kernel/time/tick-sched.c:317 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 get_ctx kernel/kcsan/core.c:206 [inline] check_access kernel/kcsan/core.c:750 [inline] __tsan_read8+0xd5/0x190 kernel/kcsan/core.c:1025 xt_get_this_cpu_counter include/linux/netfilter/x_tables.h:449 [inline] ipt_do_table+0x6e5/0xb40 net/ipv4/netfilter/ip_tables.c:297 iptable_mangle_hook+0x109/0x250 net/ipv4/netfilter/iptable_mangle.c:80 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_rcv+0x11f/0x160 net/ipv4/ip_input.c:612 __netif_receive_skb_one_core net/core/dev.c:6206 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0x333/0x680 net/core/dev.c:6670 __napi_poll+0x61/0x300 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x456/0x930 net/core/dev.c:7949 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+0x6b1/0x6f0 net/core/skbuff.c:699 alloc_skb include/linux/skbuff.h:1384 [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+0x18b/0x630 drivers/net/netdevsim/dev.c:922 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405 worker_thread+0x569/0x750 kernel/workqueue.c:3486 kthread+0x221/0x270 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 1: wq_worker_tick+0x64/0x240 kernel/workqueue.c:1508 sched_tick+0xbc/0x1f0 kernel/sched/core.c:5804 update_process_times+0x15e/0x190 kernel/time/timer.c:2480 tick_sched_handle kernel/time/tick-sched.c:296 [inline] tick_nohz_handler+0x227/0x380 kernel/time/tick-sched.c:317 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 check_access kernel/kcsan/core.c:747 [inline] __tsan_unaligned_write1+0xe8/0x180 kernel/kcsan/core.c:1022 nft_set_pktinfo_ipv4 include/net/netfilter/nf_tables_ipv4.h:13 [inline] nft_do_chain_inet+0x15d/0x320 net/netfilter/nft_chain_filter.c:153 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:481 [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:6206 [inline] __netif_receive_skb net/core/dev.c:6319 [inline] process_backlog+0x333/0x680 net/core/dev.c:6670 __napi_poll+0x61/0x300 net/core/dev.c:7729 napi_poll net/core/dev.c:7792 [inline] net_rx_action+0x456/0x930 net/core/dev.c:7949 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+0x521/0x630 drivers/net/netdevsim/dev.c:922 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405 worker_thread+0x569/0x750 kernel/workqueue.c:3486 kthread+0x221/0x270 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: 0x0000000002857260 -> 0x0000000002859970 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 3669 Comm: kworker/u8:8 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 ==================================================================