[moderation] [kernel?] KCSAN: data-race in do_mq_timedreceive / do_mq_timedreceive (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3a8660878839 Linux 6.18-rc1
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=136b9dcd980000
kernel config: https://syzkaller.appspot.com/x/.config?x=bafeb347352dd60e
dashboard link: https://syzkaller.appspot.com/bug?extid=ef0e42a6735945e1d74e
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/716425d8a25c/disk-3a866087.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7ef133e1ca3c/vmlinux-3a866087.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ef381199ff0e/bzImage-3a866087.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ef0e42...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in do_mq_timedreceive / do_mq_timedreceive

write to 0xffff888102274650 of 8 bytes by task 24558 on cpu 0:
do_mq_timedreceive+0x29a/0x6d0 ipc/mqueue.c:1216
__do_sys_mq_timedreceive ipc/mqueue.c:1283 [inline]
__se_sys_mq_timedreceive ipc/mqueue.c:1272 [inline]
__x64_sys_mq_timedreceive+0xc6/0x160 ipc/mqueue.c:1272
x64_sys_call+0x290a/0x3000 arch/x86/include/generated/asm/syscalls_64.h:244
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888102274650 of 8 bytes by task 24547 on cpu 1:
do_mq_timedreceive+0x201/0x6d0 ipc/mqueue.c:1208
__do_sys_mq_timedreceive ipc/mqueue.c:1283 [inline]
__se_sys_mq_timedreceive ipc/mqueue.c:1272 [inline]
__x64_sys_mq_timedreceive+0xc6/0x160 ipc/mqueue.c:1272
x64_sys_call+0x290a/0x3000 arch/x86/include/generated/asm/syscalls_64.h:244
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88812fc81b00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 24547 Comm: syz.2.7452 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================


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