[moderation] [kernel?] KCSAN: data-race in hrtimer_reprogram / print_cpu (12)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 59b723cd2adb Linux 6.12-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124ea587980000
kernel config: https://syzkaller.appspot.com/x/.config?x=8028551073794907
dashboard link: https://syzkaller.appspot.com/bug?extid=47ebcf8d96df0c45cad5
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [anna-...@linutronix.de fred...@kernel.org linux-...@vger.kernel.org tg...@linutronix.de]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8d84c2d12f12/disk-59b723cd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c0ff3c71ea7b/vmlinux-59b723cd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/03a664475a5c/bzImage-59b723cd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+47ebcf...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in hrtimer_reprogram / print_cpu

write to 0xffff888237d1ffa0 of 8 bytes by task 27269 on cpu 1:
__hrtimer_reprogram kernel/time/hrtimer.c:657 [inline]
hrtimer_reprogram+0x1a2/0x220 kernel/time/hrtimer.c:864
hrtimer_start_range_ns+0x512/0x580 kernel/time/hrtimer.c:1303
hrtimer_start_expires include/linux/hrtimer.h:289 [inline]
hrtimer_restart include/linux/hrtimer.h:297 [inline]
common_hrtimer_rearm+0xa6/0xc0 kernel/time/posix-timers.c:249
posixtimer_rearm+0xc7/0x1a0 kernel/time/posix-timers.c:267
dequeue_signal+0x273/0x420 kernel/signal.c:694
get_signal+0x376/0x1070 kernel/signal.c:2797
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237d1ffa0 of 8 bytes by task 27279 on cpu 0:
print_cpu+0x2fb/0x670 kernel/time/timer_list.c:133
timer_list_show+0x115/0x180 kernel/time/timer_list.c:295
seq_read_iter+0x2d1/0x930 fs/seq_file.c:230
proc_reg_read_iter+0x118/0x190 fs/proc/inode.c:299
copy_splice_read+0x3a0/0x5d0 fs/splice.c:365
do_splice_read fs/splice.c:985 [inline]
splice_direct_to_actor+0x269/0x670 fs/splice.c:1089
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0xd7/0x150 fs/splice.c:1233
do_sendfile+0x39b/0x970 fs/read_write.c:1388
__do_sys_sendfile64 fs/read_write.c:1455 [inline]
__se_sys_sendfile64 fs/read_write.c:1441 [inline]
__x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1441
x64_sys_call+0xed5/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000569a149a4d -> 0x000000569a0e2b82

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 27279 Comm: syz.5.6581 Tainted: G W 6.12.0-rc6-syzkaller #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================
loop5: detected capacity change from 0 to 1024
EXT4-fs: quotafile must be on filesystem root


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.