syzbot


KCSAN: data-race in clockevents_program_min_delta / print_tickdevice (5)

Status: moderation: reported on 2025/03/10 10:17
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+4666e46d6ba0c99ac89e@syzkaller.appspotmail.com
First crash: 1d19h, last: 1d19h
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in clockevents_program_min_delta / print_tickdevice (3) kernel 1 667d 667d 0/28 auto-obsoleted due to no activity on 2023/06/18 09:00
upstream KCSAN: data-race in clockevents_program_min_delta / print_tickdevice kernel 2 903d 904d 0/28 auto-obsoleted due to no activity on 2022/10/25 15:55
upstream KCSAN: data-race in clockevents_program_min_delta / print_tickdevice (2) kernel 6 725d 846d 0/28 auto-obsoleted due to no activity on 2023/04/25 16:15
upstream KCSAN: data-race in clockevents_program_min_delta / print_tickdevice (4) kernel 1 219d 219d 0/28 auto-obsoleted due to no activity on 2024/09/08 12:24

Sample crash report:
==================================================================
BUG: KCSAN: data-race in clockevents_program_min_delta / print_tickdevice

read-write to 0xffff888237d1c240 of 8 bytes by task 5825 on cpu 1:
 clockevents_program_min_delta+0xb6/0x260 kernel/time/clockevents.c:246
 clockevents_program_event+0x180/0x1f0
 tick_program_event+0x7c/0xd0 kernel/time/tick-oneshot.c:44
 __hrtimer_reprogram kernel/time/hrtimer.c:697 [inline]
 hrtimer_reprogram+0x1cf/0x220 kernel/time/hrtimer.c:880
 hrtimer_start_range_ns+0x699/0x720 kernel/time/hrtimer.c:1344
 hrtimer_start_expires include/linux/hrtimer.h:274 [inline]
 hrtimer_restart include/linux/hrtimer.h:282 [inline]
 common_hrtimer_rearm+0xa9/0xc0 kernel/time/posix-timers.c:250
 __posixtimer_deliver_signal kernel/time/posix-timers.c:268 [inline]
 posixtimer_deliver_signal+0x10c/0x2e0 kernel/time/posix-timers.c:294
 dequeue_signal+0x2a5/0x370 kernel/signal.c:659
 get_signal+0x376/0x1000 kernel/signal.c:2916
 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:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x62/0x120 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 0xffff888237d1c240 of 8 bytes by task 5897 on cpu 0:
 print_tickdevice+0x2ae/0x340 kernel/time/timer_list.c:234
 timer_list_show+0x79/0x180 kernel/time/timer_list.c:300
 seq_read_iter+0x2d1/0x930 fs/seq_file.c:230
 proc_reg_read_iter+0x118/0x190 fs/proc/inode.c:299
 copy_splice_read+0x383/0x5b0 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+0x398/0x660 fs/read_write.c:1363
 __do_sys_sendfile64 fs/read_write.c:1424 [inline]
 __se_sys_sendfile64 fs/read_write.c:1410 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1410
 x64_sys_call+0xfbd/0x2dc0 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: 0x000000000003d3f7 -> 0x000000000003d3f8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 5897 Comm: syz.1.760 Not tainted 6.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/10 10:17 upstream 80e54e84911a 163f510d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in clockevents_program_min_delta / print_tickdevice
* Struck through repros no longer work on HEAD.