syzbot


KCSAN: data-race in clockevents_program_event / print_tickdevice (12)

Status: moderation: reported on 2025/07/07 18:12
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+0a9e9ee5e8f45fd819a9@syzkaller.appspotmail.com
First crash: 106d, last: 4d19h
Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (8) kernel 6 1 672d 672d 0/29 auto-obsoleted due to no activity on 2024/01/23 08:37
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (6) kernel 6 28 858d 1150d 0/29 auto-obsoleted due to no activity on 2023/07/21 02:50
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (11) kernel 6 1 202d 202d 0/29 auto-obsoleted due to no activity on 2025/05/27 18:27
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (7) kernel 6 2 725d 726d 0/29 auto-obsoleted due to no activity on 2023/11/30 21:56
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (5) kernel 6 7 1197d 1223d 0/29 auto-closed as invalid on 2022/08/15 19:00
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (2) kernel 6 1 1558d 1558d 0/29 auto-closed as invalid on 2021/08/19 20:40
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (10) kernel 6 2 417d 423d 0/29 auto-obsoleted due to no activity on 2024/10/04 08:26
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (9) kernel 6 1 560d 560d 0/29 auto-obsoleted due to no activity on 2024/05/13 19:49
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (4) kernel 6 1 1347d 1347d 0/29 auto-closed as invalid on 2022/03/19 14:36
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice kernel 6 1 1642d 1638d 0/29 auto-closed as invalid on 2021/05/28 09:07
upstream KCSAN: data-race in clockevents_program_event / print_tickdevice (3) kernel 6 5 1448d 1479d 0/29 auto-closed as invalid on 2021/12/08 10:38

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

read-write to 0xffff888237d17780 of 8 bytes by task 15264 on cpu 1:
 clockevents_program_min_delta kernel/time/clockevents.c:246 [inline]
 clockevents_program_event+0x38a/0x4e0 kernel/time/clockevents.c:328
 tick_program_event+0x79/0xc0 kernel/time/tick-oneshot.c:44
 __hrtimer_reprogram kernel/time/hrtimer.c:678 [inline]
 hrtimer_reprogram+0x1d4/0x220 kernel/time/hrtimer.c:861
 hrtimer_start_range_ns+0x6b1/0x740 kernel/time/hrtimer.c:1323
 hrtimer_start_expires include/linux/hrtimer.h:273 [inline]
 hrtimer_restart include/linux/hrtimer.h:281 [inline]
 common_hrtimer_rearm+0x85/0x90 kernel/time/posix-timers.c:303
 __posixtimer_deliver_signal kernel/time/posix-timers.c:321 [inline]
 posixtimer_deliver_signal+0x120/0x320 kernel/time/posix-timers.c:347
 dequeue_signal+0x2cf/0x3b0 kernel/signal.c:660
 get_signal+0x376/0xf70 kernel/signal.c:2914
 arch_do_signal_or_restart+0x96/0x440 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x77/0x110 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237d17780 of 8 bytes by task 15270 on cpu 0:
 print_tickdevice+0x2ab/0x340 kernel/time/timer_list.c:232
 timer_list_show+0x6c/0x170 kernel/time/timer_list.c:298
 seq_read_iter+0x636/0x950 fs/seq_file.c:272
 proc_reg_read_iter+0x110/0x180 fs/proc/inode.c:299
 copy_splice_read+0x442/0x660 fs/splice.c:363
 do_splice_read fs/splice.c:982 [inline]
 splice_direct_to_actor+0x26f/0x680 fs/splice.c:1086
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2bb4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 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: 0x0000000000065d9f -> 0x0000000000065da0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 15270 Comm: syz.4.4141 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/16 22:50 upstream 98ac9cc4b445 19568248 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in clockevents_program_event / print_tickdevice
2025/09/01 08:54 upstream b320789d6883 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in clockevents_program_event / print_tickdevice
2025/07/24 01:23 upstream 01a412d06bc5 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in clockevents_program_event / print_tickdevice
2025/07/07 18:11 upstream d7b8f8e20813 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in clockevents_program_event / print_tickdevice
* Struck through repros no longer work on HEAD.