[moderation] [can?] KCSAN: data-race in can_rcv_filter / can_rx_register (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: aacb0a6d604a Merge tag 'pmdomain-v6.19-rc3' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=151de69a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b319ff1b6a2797ca
dashboard link: https://syzkaller.appspot.com/bug?extid=eaeea5547ee9e0e40d8f
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [linu...@vger.kernel.org linux-...@vger.kernel.org m...@pengutronix.de sock...@hartkopp.net]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fb50ebef3bc0/disk-aacb0a6d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3c357a711af6/vmlinux-aacb0a6d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/926530a78dea/bzImage-aacb0a6d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eaeea5...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in can_rcv_filter / can_rx_register

read-write to 0xffff88810507e020 of 4 bytes by task 8625 on cpu 1:
can_rx_register+0x46c/0x4d0 net/can/af_can.c:479
bcm_rx_setup+0xb0d/0xe10 net/can/bcm.c:1300
bcm_sendmsg+0x1b2/0x480 net/can/bcm.c:1427
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x145/0x180 net/socket.c:742
____sys_sendmsg+0x31e/0x4a0 net/socket.c:2592
___sys_sendmsg+0x17b/0x1d0 net/socket.c:2646
__sys_sendmsg net/socket.c:2678 [inline]
__do_sys_sendmsg net/socket.c:2683 [inline]
__se_sys_sendmsg net/socket.c:2681 [inline]
__x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681
x64_sys_call+0x17ba/0x3000 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810507e020 of 4 bytes by interrupt on cpu 0:
can_rcv_filter+0x40/0x4f0 net/can/af_can.c:586
can_receive+0xfb/0x1c0 net/can/af_can.c:662
canfd_rcv+0xed/0x190 net/can/af_can.c:705
__netif_receive_skb_one_core net/core/dev.c:6139 [inline]
__netif_receive_skb+0x120/0x270 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
run_ksoftirqd+0x1c/0x30 kernel/softirq.c:1063
smpboot_thread_fn+0x32b/0x530 kernel/smpboot.c:160
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: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 14 Comm: ksoftirqd/0 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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