syzbot


KCSAN: data-race in __lookup_mnt / umount_tree (7)

Status: auto-obsoleted due to no activity on 2024/05/14 04:41
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+c4b5521171c434a60c03@syzkaller.appspotmail.com
First crash: 42d, last: 42d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __lookup_mnt / umount_tree (4) fs 1 624d 624d 0/26 auto-obsoleted due to no activity on 2022/10/10 17:50
upstream KCSAN: data-race in __lookup_mnt / umount_tree (3) fs 1 778d 778d 0/26 auto-closed as invalid on 2022/05/09 13:18
upstream KCSAN: data-race in __lookup_mnt / umount_tree (2) fs 1 925d 925d 0/26 auto-closed as invalid on 2021/12/13 12:07
upstream KCSAN: data-race in __lookup_mnt / umount_tree fs 1 1096d 1096d 0/26 auto-closed as invalid on 2021/06/25 00:51
upstream KCSAN: data-race in __lookup_mnt / umount_tree (5) fs 1 259d 259d 0/26 auto-obsoleted due to no activity on 2023/10/10 19:57
upstream KCSAN: data-race in __lookup_mnt / umount_tree (6) fs 3 180d 163d 0/26 auto-obsoleted due to no activity on 2023/12/27 23:51

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __lookup_mnt / umount_tree

write to 0xffff888115bb4010 of 8 bytes by task 6801 on cpu 0:
 unhash_mnt fs/namespace.c:891 [inline]
 umount_mnt fs/namespace.c:906 [inline]
 umount_tree+0x625/0x910 fs/namespace.c:1673
 path_umount+0x991/0xa10 fs/namespace.c:1896
 ksys_umount fs/namespace.c:1919 [inline]
 __do_sys_umount fs/namespace.c:1924 [inline]
 __se_sys_umount fs/namespace.c:1922 [inline]
 __x64_sys_umount+0xb9/0xe0 fs/namespace.c:1922
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

read to 0xffff888115bb4010 of 8 bytes by task 6803 on cpu 1:
 __lookup_mnt+0x83/0xf0 fs/namespace.c:701
 __follow_mount_rcu fs/namei.c:1506 [inline]
 handle_mounts fs/namei.c:1536 [inline]
 step_into+0x434/0x810 fs/namei.c:1842
 walk_component+0x169/0x230 fs/namei.c:2010
 lookup_last fs/namei.c:2461 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2485
 filename_lookup+0x127/0x300 fs/namei.c:2514
 user_path_at_empty+0x42/0x120 fs/namei.c:2921
 user_path_at include/linux/namei.h:57 [inline]
 ksys_umount fs/namespace.c:1916 [inline]
 __do_sys_umount fs/namespace.c:1924 [inline]
 __se_sys_umount fs/namespace.c:1922 [inline]
 __x64_sys_umount+0x88/0xe0 fs/namespace.c:1922
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0xffff888104009980 -> 0xffff888115bb4000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 6803 Comm: syz-executor.4 Tainted: G        W          6.9.0-rc3-syzkaller-00011-g20cb38a7af88 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/09 04:41 upstream 20cb38a7af88 f3234354 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __lookup_mnt / umount_tree
* Struck through repros no longer work on HEAD.