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KCSAN: data-race in do_epoll_wait / ep_poll_callback (12)

Status: moderation: reported on 2025/02/08 04:24
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+d4d7d5b209df3c207199@syzkaller.appspotmail.com
First crash: 13d, last: 13d
Similar bugs (11)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (7) fs 1 1111d 1111d 0/28 auto-closed as invalid on 2022/03/12 11:24
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (9) fs 9 726d 845d 0/28 auto-obsoleted due to no activity on 2023/04/08 19:56
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (11) fs 3 328d 357d 0/28 auto-obsoleted due to no activity on 2024/05/03 13:41
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (6) fs 1 1153d 1153d 0/28 auto-closed as invalid on 2022/01/29 14:05
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (2) fs 2 1475d 1477d 0/28 auto-closed as invalid on 2021/03/14 02:07
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (5) fs 2 1259d 1270d 0/28 auto-closed as invalid on 2021/10/15 22:14
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (4) fs 1 1352d 1352d 0/28 auto-closed as invalid on 2021/07/14 13:56
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (3) fs 1 1422d 1422d 0/28 auto-closed as invalid on 2021/05/17 11:16
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (8) fs 1 1061d 1061d 0/28 auto-closed as invalid on 2022/05/01 05:30
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback fs 221 1662d 1699d 0/28 auto-closed as invalid on 2020/08/31 10:40
upstream KCSAN: data-race in do_epoll_wait / ep_poll_callback (10) fs 2 452d 438d 0/28 auto-obsoleted due to no activity on 2024/01/01 00:54

Sample crash report:
==================================================================
BUG: KCSAN: data-race in do_epoll_wait / ep_poll_callback

write to 0xffff88814e9258e8 of 4 bytes by task 31648 on cpu 0:
 ep_send_events fs/eventpoll.c:1920 [inline]
 ep_poll fs/eventpoll.c:2039 [inline]
 do_epoll_wait+0x88b/0x1060 fs/eventpoll.c:2484
 do_epoll_pwait fs/eventpoll.c:2514 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2527 [inline]
 __se_sys_epoll_pwait+0x15f/0x280 fs/eventpoll.c:2521
 __x64_sys_epoll_pwait+0x78/0x90 fs/eventpoll.c:2521
 x64_sys_call+0xc00/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:282
 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

read to 0xffff88814e9258e8 of 4 bytes by task 31651 on cpu 1:
 ep_poll_callback+0x4f0/0x600 fs/eventpoll.c:1420
 __wake_up_common kernel/sched/wait.c:89 [inline]
 __wake_up_common_lock kernel/sched/wait.c:106 [inline]
 __wake_up+0x65/0xb0 kernel/sched/wait.c:127
 do_notify_pidfd kernel/signal.c:2156 [inline]
 do_notify_parent+0x1e6/0x5b0 kernel/signal.c:2187
 exit_notify kernel/exit.c:758 [inline]
 do_exit+0xdd7/0x17f0 kernel/exit.c:958
 __do_sys_exit kernel/exit.c:1054 [inline]
 __se_sys_exit kernel/exit.c:1052 [inline]
 __x64_sys_exit+0x1f/0x20 kernel/exit.c:1052
 x64_sys_call+0x2da1/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:61
 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: 0xe000203b -> 0xe0000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 31651 Comm: syz.1.23497 Not tainted 6.14.0-rc1-syzkaller-00181-g7ee983c850b4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/08 04:23 upstream 7ee983c850b4 ef44b750 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in do_epoll_wait / ep_poll_callback
* Struck through repros no longer work on HEAD.