syzbot


KCSAN: data-race in __ep_remove / __fput (4)

Status: upstream: reported on 2024/07/04 14:38
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+3195ed1f3a2ab8bea49a@syzkaller.appspotmail.com
First crash: 11d, last: 11d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [fs?] KCSAN: data-race in __ep_remove / __fput (4) 2 (3) 2024/07/05 10:34
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __ep_remove / __fput (3) fs 1 155d 155d 0/27 auto-obsoleted due to no activity on 2024/03/14 21:07
upstream KCSAN: data-race in __ep_remove / __fput fs 1 383d 383d 0/27 auto-obsoleted due to no activity on 2023/07/30 19:06
upstream KCSAN: data-race in __ep_remove / __fput (2) fs 1 342d 342d 0/27 auto-obsoleted due to no activity on 2023/09/09 12:48

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __ep_remove / __fput

write to 0xffff88810f2358d0 of 8 bytes by task 6036 on cpu 1:
 __ep_remove+0x3c9/0x450 fs/eventpoll.c:826
 ep_remove_safe fs/eventpoll.c:864 [inline]
 ep_clear_and_put+0x158/0x260 fs/eventpoll.c:900
 ep_eventpoll_release+0x32/0x50 fs/eventpoll.c:937
 __fput+0x2c2/0x660 fs/file_table.c:422
 ____fput+0x15/0x20 fs/file_table.c:450
 task_work_run+0x13a/0x1a0 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [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+0xbe/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 0xffff88810f2358d0 of 8 bytes by task 6037 on cpu 0:
 eventpoll_release include/linux/eventpoll.h:45 [inline]
 __fput+0x234/0x660 fs/file_table.c:413
 ____fput+0x15/0x20 fs/file_table.c:450
 task_work_run+0x13a/0x1a0 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [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+0xbe/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888102f1e010 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6037 Comm: syz.0.1032 Not tainted 6.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/07/01 15:52 upstream 22a40d14b572 b294e901 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __ep_remove / __fput
* Struck through repros no longer work on HEAD.