================================================================== BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick read-write to 0xffff8881000738b8 of 8 bytes by interrupt on cpu 1: wq_worker_tick+0x60/0x230 kernel/workqueue.c:1474 sched_tick+0xd7/0x220 kernel/sched/core.c:5546 update_process_times+0x15f/0x190 kernel/time/timer.c:2479 tick_sched_handle kernel/time/tick-sched.c:298 [inline] tick_nohz_handler+0x276/0x3d0 kernel/time/tick-sched.c:319 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x20f/0x5a0 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x21a/0x460 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1d0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 is_atomic kernel/kcsan/core.c:260 [inline] should_watch kernel/kcsan/core.c:277 [inline] check_access kernel/kcsan/core.c:752 [inline] __tsan_read1+0xf8/0x180 kernel/kcsan/core.c:1022 __nf_ct_ext_exist include/net/netfilter/nf_conntrack_extend.h:47 [inline] nf_ct_ext_find include/net/netfilter/nf_conntrack_extend.h:61 [inline] nfct_nat include/net/netfilter/nf_nat.h:51 [inline] nf_nat_inet_fn+0x10d/0x690 net/netfilter/nf_nat_core.c:922 nf_nat_ipv4_fn net/netfilter/nf_nat_proto.c:602 [inline] nf_nat_ipv4_pre_routing+0x124/0x210 net/netfilter/nf_nat_proto.c:612 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0x78/0x180 net/netfilter/core.c:623 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK include/linux/netfilter.h:316 [inline] ip_rcv+0xfe/0x140 net/ipv4/ip_input.c:573 __netif_receive_skb_one_core net/core/dev.c:6139 [inline] __netif_receive_skb+0xff/0x270 net/core/dev.c:6252 process_backlog+0x228/0x420 net/core/dev.c:6604 __napi_poll+0x5f/0x300 net/core/dev.c:7668 napi_poll net/core/dev.c:7731 [inline] net_rx_action+0x425/0x8c0 net/core/dev.c:7883 handle_softirqs+0xba/0x290 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+0x476/0x4b0 net/core/skbuff.c:674 alloc_skb include/linux/skbuff.h:1383 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:818 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:875 [inline] nsim_dev_trap_report_work+0x18a/0x630 drivers/net/netdevsim/dev.c:921 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340 worker_thread+0x582/0x770 kernel/workqueue.c:3421 kthread+0x489/0x510 kernel/kthread.c:463 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 read-write to 0xffff8881000738b8 of 8 bytes by interrupt on cpu 0: wq_worker_tick+0x60/0x230 kernel/workqueue.c:1474 sched_tick+0xd7/0x220 kernel/sched/core.c:5546 update_process_times+0x15f/0x190 kernel/time/timer.c:2479 tick_sched_handle kernel/time/tick-sched.c:298 [inline] tick_nohz_handler+0x276/0x3d0 kernel/time/tick-sched.c:319 __run_hrtimer kernel/time/hrtimer.c:1777 [inline] __hrtimer_run_queues+0x20f/0x5a0 kernel/time/hrtimer.c:1841 hrtimer_interrupt+0x21a/0x460 kernel/time/hrtimer.c:1903 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1d0 arch/x86/kernel/apic/apic.c:1062 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1056 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 kcsan_setup_watchpoint+0x406/0x420 kernel/kcsan/core.c:705 ipt_do_table+0x1d3/0xab0 net/ipv4/netfilter/ip_tables.c:263 ipt_mangle_out net/ipv4/netfilter/iptable_mangle.c:53 [inline] iptable_mangle_hook+0xd6/0x260 net/ipv4/netfilter/iptable_mangle.c:79 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0x78/0x180 net/netfilter/core.c:623 nf_hook include/linux/netfilter.h:273 [inline] __ip_local_out+0x2cb/0x2f0 net/ipv4/ip_output.c:120 ip_local_out+0x2a/0xe0 net/ipv4/ip_output.c:129 synproxy_send_tcp+0x2ae/0x2f0 net/netfilter/nf_synproxy_core.c:439 synproxy_send_client_synack+0x57c/0x5d0 net/netfilter/nf_synproxy_core.c:484 nft_synproxy_eval_v4+0x22a/0x280 net/netfilter/nft_synproxy.c:59 nft_synproxy_do_eval+0x1cf/0x270 net/netfilter/nft_synproxy.c:141 nft_synproxy_eval+0x29/0x40 net/netfilter/nft_synproxy.c:247 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x1e2/0xc90 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x1eb/0x220 net/netfilter/nft_chain_filter.c:161 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0x78/0x180 net/netfilter/core.c:623 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK include/linux/netfilter.h:316 [inline] ip_local_deliver+0x178/0x1c0 net/ipv4/ip_input.c:262 dst_input include/net/dst.h:474 [inline] ip_rcv_finish+0x194/0x1c0 net/ipv4/ip_input.c:453 NF_HOOK include/linux/netfilter.h:318 [inline] ip_rcv+0x62/0x140 net/ipv4/ip_input.c:573 __netif_receive_skb_one_core net/core/dev.c:6139 [inline] __netif_receive_skb+0xff/0x270 net/core/dev.c:6252 process_backlog+0x228/0x420 net/core/dev.c:6604 __napi_poll+0x5f/0x300 net/core/dev.c:7668 napi_poll net/core/dev.c:7731 [inline] net_rx_action+0x425/0x8c0 net/core/dev.c:7883 handle_softirqs+0xba/0x290 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+0x476/0x4b0 net/core/skbuff.c:674 alloc_skb include/linux/skbuff.h:1383 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:818 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:875 [inline] nsim_dev_trap_report_work+0x18a/0x630 drivers/net/netdevsim/dev.c:921 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340 worker_thread+0x582/0x770 kernel/workqueue.c:3421 kthread+0x489/0x510 kernel/kthread.c:463 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 value changed: 0x00000000053aa750 -> 0x00000000053ace60 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 41 Comm: kworker/u8:2 Not tainted syzkaller #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: events_unbound nsim_dev_trap_report_work ==================================================================