syzbot


KCSAN: data-race in __lookup_mnt / umount_tree (2)

Status: auto-closed as invalid on 2021/12/13 12:07
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 390d, last: 390d
similar bugs (3):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __lookup_mnt / umount_tree (4) 1 88d 88d 0/24 auto-obsoleted due to no activity on 2022/10/10 17:50
upstream KCSAN: data-race in __lookup_mnt / umount_tree (3) 1 242d 242d 0/24 auto-closed as invalid on 2022/05/09 13:18
upstream KCSAN: data-race in __lookup_mnt / umount_tree 1 561d 561d 0/24 auto-closed as invalid on 2021/06/25 00:51

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

write to 0xffff888105e44990 of 8 bytes by task 9724 on cpu 1:
 unhash_mnt fs/namespace.c:839 [inline]
 umount_mnt fs/namespace.c:854 [inline]
 umount_tree+0x5ad/0x8f0 fs/namespace.c:1545
 path_umount+0x9df/0xa70 fs/namespace.c:1753
 ksys_umount fs/namespace.c:1776 [inline]
 __do_sys_umount fs/namespace.c:1781 [inline]
 __se_sys_umount fs/namespace.c:1779 [inline]
 __x64_sys_umount+0xb5/0xe0 fs/namespace.c:1779
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888105e44990 of 8 bytes by task 9725 on cpu 0:
 __lookup_mnt+0x89/0xf0 fs/namespace.c:630
 __follow_mount_rcu fs/namei.c:1450 [inline]
 handle_mounts fs/namei.c:1486 [inline]
 step_into+0x35c/0xee0 fs/namei.c:1800
 walk_component+0x1a1/0x360 fs/namei.c:1976
 lookup_last fs/namei.c:2425 [inline]
 path_lookupat+0x12d/0x3d0 fs/namei.c:2449
 filename_lookup+0x130/0x310 fs/namei.c:2478
 user_path_at_empty+0x3e/0x110 fs/namei.c:2801
 user_path_at include/linux/namei.h:57 [inline]
 do_mount fs/namespace.c:3328 [inline]
 __do_sys_mount fs/namespace.c:3539 [inline]
 __se_sys_mount+0x217/0x2f0 fs/namespace.c:3516
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3516
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff888101b84840 -> 0xffff888105e44980

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9725 Comm: syz-executor.2 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2021/11/08 12:02 upstream 6b75d88fa81b d29682f1 .config log report info KCSAN: data-race in __lookup_mnt / umount_tree
* Struck through repros no longer work on HEAD.