KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv (6)

Status: moderation: reported on 2026/10/21 01:24
Subsystems: can
Labels: race:benign
[Documentation on labels]
Reported-by: syzbot+a6205fafcbfe69a5fd67@syzkaller.appspotmail.com
First crash: 13h53m, last: 13h53m
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
5b9f0c33 assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv (6) 2026/10/21 02:07 2026/10/21 02:07 2026/10/21 03:06 61c200c7
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv can 6 4 893d 938d 0/29 auto-obsoleted due to no activity on 2024/06/14 15:49
upstream KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv (4) can 6 9 409d 502d 0/29 auto-obsoleted due to no activity on 2025/11/02 07:50
upstream KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv (3) can 6 4 606d 591d 0/29 auto-obsoleted due to no activity on 2025/04/19 08:20
upstream KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv (2) can 6 1 715d 715d 0/29 auto-obsoleted due to no activity on 2024/12/30 16:15
upstream KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv (5) prio:normal can 6 53 60d 310d 0/29 auto-obsoleted due to no activity on 2026/10/17 07:42

Sample crash report:
IN= OUT=eth0 SRC=10.128.1.152 DST=10.128.0.163 LEN=52 TOS=0x00 PREC=0x00 TTL=64 ID=48410 DF PROTO=TCP SPT=43180 DPT=30036 WINDOW=2872 RES=0x00 ACK URGP=0 
==================================================================
BUG: KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv

read-write to 0xffff88811ca21620 of 4 bytes by interrupt on cpu 1:
 can_can_gw_rcv+0x858/0x860 net/can/gw.c:575
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0x44/0xe0 kernel/softirq.c:758
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 constant_test_bit arch/x86/include/asm/bitops.h:202 [inline]
 arch_test_bit arch/x86/include/asm/bitops.h:232 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
 folio_test_swapbacked include/linux/page-flags.h:572 [inline]
 mm_counter_file include/linux/mm.h:3489 [inline]
 mm_counter include/linux/mm.h:3498 [inline]
 zap_present_folio_ptes mm/memory.c:1789 [inline]
 zap_present_ptes mm/memory.c:1861 [inline]
 do_zap_pte_range mm/memory.c:1963 [inline]
 zap_pte_range mm/memory.c:2065 [inline]
 zap_pmd_range mm/memory.c:2151 [inline]
 zap_pud_range mm/memory.c:2179 [inline]
 zap_p4d_range mm/memory.c:2200 [inline]
 __zap_vma_range+0x144c/0x2c50 mm/memory.c:2240
 unmap_vmas+0x1fb/0x2e0 mm/memory.c:2309
 exit_mmap+0x1a2/0x5e0 mm/mmap.c:1315
 __mmput+0x28/0x1c0 kernel/fork.c:1193
 mmput+0x3b/0x50 kernel/fork.c:1216
 exit_mm+0x11b/0x1b0 kernel/exit.c:592
 do_exit+0x445/0x14f0 kernel/exit.c:974
 do_group_exit+0xfe/0x140 kernel/exit.c:1130
 get_signal+0xe02/0xf00 kernel/signal.c:3112
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x15d/0x8c0 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline]
 do_syscall_64+0x212/0x360 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read-write to 0xffff88811ca21620 of 4 bytes by interrupt on cpu 0:
 can_can_gw_rcv+0x858/0x860 net/can/gw.c:575
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0x44/0xe0 kernel/softirq.c:758
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 kcsan_setup_watchpoint+0x42b/0x4a0 kernel/kcsan/core.c:713
 io_nop+0x21f/0x2c0 io_uring/nop.c:-1
 __io_issue_sqe+0xfd/0x2e0 io_uring/io_uring.c:1388
 io_issue_sqe+0x1e7/0xb80 io_uring/io_uring.c:1411
 io_queue_sqe io_uring/io_uring.c:1642 [inline]
 io_submit_sqe io_uring/io_uring.c:1927 [inline]
 io_submit_sqes+0x7e1/0x1180 io_uring/io_uring.c:2050
 __do_sys_io_uring_enter io_uring/io_uring.c:2640 [inline]
 __se_sys_io_uring_enter+0x25c/0xf90 io_uring/io_uring.c:2589
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:2589
 x64_sys_call+0x1780/0x2550 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000015b6 -> 0x000015b7

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 18058 Comm: syz.1.6046 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================
IN= OUT=eth0 SRC=10.128.1.152 DST=10.128.0.163 LEN=52 TOS=0x00 PREC=0x00 TTL=64 ID=48411 DF PROTO=TCP SPT=43180 DPT=30036 WINDOW=2872 RES=0x00 ACK URGP=0 
ip6_tunnel: ip6gretap0: Local routing loop detected!
==================================================================
BUG: KCSAN: data-race in vxcan_xmit / vxcan_xmit

read-write to 0xffff88811b0b8230 of 8 bytes by interrupt on cpu 1:
 vxcan_xmit+0x2d0/0x380 drivers/net/can/vxcan.c:91
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0x44/0xe0 kernel/softirq.c:758
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:123 [inline]
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:211 [inline]
 _raw_spin_unlock_irqrestore+0x1a/0x30 kernel/locking/spinlock.c:221
 spin_unlock_irqrestore include/linux/spinlock.h:425 [inline]
 __uart_port_unlock_irqrestore include/linux/serial_core.h:622 [inline]
 univ8250_console_device_unlock+0x36/0x40 drivers/tty/serial/8250/8250_core.c:420
 nbcon_emit_one kernel/printk/nbcon.c:1165 [inline]
 nbcon_kthread_func+0x5e0/0x6d0 kernel/printk/nbcon.c:1271
 kthread+0x223/0x270 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 0xffff88811b0b8230 of 8 bytes by interrupt on cpu 0:
 vxcan_xmit+0x2d0/0x380 drivers/net/can/vxcan.c:91
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 do_softirq+0x46/0x60 kernel/softirq.c:546
 __local_bh_enable_ip+0x79/0x80 kernel/softirq.c:473
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 __alloc_skb+0x6b6/0x6f0 net/core/skbuff.c:699
 alloc_skb include/linux/skbuff.h:1384 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:744 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:801 [inline]
 nsim_dev_trap_report_work+0x18b/0x620 drivers/net/netdevsim/dev.c:847
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x53f/0xa10 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 kthread+0x223/0x270 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: 0x00000000000052ee -> 0x00000000000052ef

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 743 Comm: kworker/u8:11 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: events_unbound nsim_dev_trap_report_work
==================================================================
==================================================================
BUG: KCSAN: data-race in vxcan_xmit / vxcan_xmit

read-write to 0xffff88811b0b8230 of 8 bytes by interrupt on cpu 1:
 vxcan_xmit+0x2d0/0x380 drivers/net/can/vxcan.c:91
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 do_softirq+0x46/0x60 kernel/softirq.c:546
 __local_bh_enable_ip+0x79/0x80 kernel/softirq.c:473
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x17/0x20 kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 neigh_periodic_work+0x5e2/0x690 net/core/neighbour.c:1035
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x53f/0xa10 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 kthread+0x223/0x270 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 0xffff88811b0b8230 of 8 bytes by interrupt on cpu 0:
 vxcan_xmit+0x2d0/0x380 drivers/net/can/vxcan.c:91
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:1099
 smpboot_thread_fn+0x372/0x560 kernel/smpboot.c:162
 kthread+0x223/0x270 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: 0x000000000004b746 -> 0x000000000004b747

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 14 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================
==================================================================
BUG: KCSAN: data-race in vxcan_xmit / vxcan_xmit

read-write to 0xffff88811b0c0228 of 8 bytes by interrupt on cpu 1:
 vxcan_xmit+0x30d/0x380 drivers/net/can/vxcan.c:94
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 do_softirq+0x46/0x60 kernel/softirq.c:546
 __local_bh_enable_ip+0x79/0x80 kernel/softirq.c:473
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x17/0x20 kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 neigh_periodic_work+0x5e2/0x690 net/core/neighbour.c:1035
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x53f/0xa10 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 kthread+0x223/0x270 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 0xffff88811b0c0228 of 8 bytes by interrupt on cpu 0:
 vxcan_xmit+0x30d/0x380 drivers/net/can/vxcan.c:94
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:1099
 smpboot_thread_fn+0x372/0x560 kernel/smpboot.c:162
 kthread+0x223/0x270 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: 0x00000000000566f0 -> 0x00000000000566f1

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 14 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
==================================================================
==================================================================
BUG: KCSAN: data-race in vxcan_xmit / vxcan_xmit

read-write to 0xffff88811b0c0228 of 8 bytes by interrupt on cpu 1:
 vxcan_xmit+0x30d/0x380 drivers/net/can/vxcan.c:94
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 do_softirq+0x46/0x60 kernel/softirq.c:546
 __local_bh_enable_ip+0x79/0x80 kernel/softirq.c:473
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x17/0x20 kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 neigh_periodic_work+0x5e2/0x690 net/core/neighbour.c:1035
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x53f/0xa10 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 kthread+0x223/0x270 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 0xffff88811b0c0228 of 8 bytes by interrupt on cpu 0:
 vxcan_xmit+0x30d/0x380 drivers/net/can/vxcan.c:94
 __netdev_start_xmit include/linux/netdevice.h:5432 [inline]
 netdev_start_xmit include/linux/netdevice.h:5441 [inline]
 xmit_one net/core/dev.c:3953 [inline]
 dev_hard_start_xmit+0x10c/0x380 net/core/dev.c:3969
 __dev_queue_xmit+0xbfd/0x1ec0 net/core/dev.c:4958
 dev_queue_xmit include/linux/netdevice.h:3464 [inline]
 can_send+0x584/0x720 net/can/af_can.c:279
 can_can_gw_rcv+0x80c/0x860 net/can/gw.c:572
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 do_softirq+0x46/0x60 kernel/softirq.c:546
 __local_bh_enable_ip+0x79/0x80 kernel/softirq.c:473
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 __alloc_skb+0x6b6/0x6f0 net/core/skbuff.c:699
 alloc_skb include/linux/skbuff.h:1384 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:744 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:801 [inline]
 nsim_dev_trap_report_work+0x18b/0x620 drivers/net/netdevsim/dev.c:847
 process_one_work kernel/workqueue.c:3396 [inline]
 process_scheduled_works+0x53f/0xa10 kernel/workqueue.c:3479
 worker_thread+0x569/0x750 kernel/workqueue.c:3560
 kthread+0x223/0x270 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: 0x00000000000a1884 -> 0x00000000000a1885

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4193 Comm: kworker/u8:18 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: events_unbound nsim_dev_trap_report_work
==================================================================
==================================================================
BUG: KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv

read-write to 0xffff88811ca21620 of 4 bytes by interrupt on cpu 1:
 can_can_gw_rcv+0x858/0x860 net/can/gw.c:575
 deliver net/can/af_can.c:575 [inline]
 can_rcv_filter+0xc3/0x480 net/can/af_can.c:602
 can_receive+0xd2/0x120 net/can/af_can.c:669
 canfd_rcv+0x1b6/0x270 net/can/af_can.c:730
 __netif_receive_skb_one_core net/core/dev.c:6297 [inline]
 __netif_receive_skb net/core/dev.c:6410 [inline]
 process_backlog+0x354/0x680 net/core/dev.c:6761
 __napi_poll+0x61/0x300 net/core/dev.c:7830
 napi_poll net/core/dev.c:7893 [inline]
 net_rx_action+0x456/0x930 net/core/dev.c:8050
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 do_softirq+0x46/0x60 kernel/softirq.c:546
 __local_bh_enable_ip+0x79/0x80 kernel/softirq.c:473
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x17/0x20 kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 release_sock+0x10c/0x180 net/core/sock.c:3907
 tcp_recvmsg+0x140/0x4b0 net/ipv4/tcp.c:2947
 inet_recvmsg+0x8d/0x210 net/ipv4/af_inet.c:894
 sock_recvmsg_nosec net/socket.c:1153 [inline]
 sock_recvmsg+0xda/0x120 net/socket.c:1173
 sock_read_iter+0x146/0x190 net/socket.c:1242
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 x64_sys_call+0x2135/0x2550 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/21 01:24 upstream 4cbdd58dfa7a df8746fb .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in can_can_gw_rcv / can_can_gw_rcv
* Struck through repros no longer work on HEAD.