syzbot


KCSAN: data-race in __dentry_kill / step_into (7)

Status: moderation: reported on 2024/05/21 16:51
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+9fd7f6da7918e432f1cd@syzkaller.appspotmail.com
First crash: 24d, last: 20d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __dentry_kill / step_into (6) fs 1 59d 59d 0/27 auto-obsoleted due to no activity on 2024/05/21 11:40
upstream KCSAN: data-race in __dentry_kill / step_into fs 1 1344d 1344d 0/27 auto-closed as invalid on 2020/11/14 02:21
upstream KCSAN: data-race in __dentry_kill / step_into (5) fs 106 105d 190d 0/27 auto-obsoleted due to no activity on 2024/04/05 18:21
upstream KCSAN: data-race in __dentry_kill / step_into (4) fs 1 839d 839d 0/27 auto-closed as invalid on 2022/04/03 02:19
upstream KCSAN: data-race in __dentry_kill / step_into (2) fs 3 1099d 1137d 0/27 auto-closed as invalid on 2021/07/16 10:59
upstream KCSAN: data-race in __dentry_kill / step_into (3) fs 5 901d 959d 0/27 auto-closed as invalid on 2022/01/30 10:25

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __dentry_kill / step_into

read-write to 0xffff888100443e40 of 4 bytes by task 24192 on cpu 0:
 dentry_unlist fs/dcache.c:548 [inline]
 __dentry_kill+0x228/0x4b0 fs/dcache.c:617
 shrink_kill fs/dcache.c:1048 [inline]
 shrink_dentry_list+0x1bc/0x3e0 fs/dcache.c:1075
 shrink_dcache_sb+0x154/0x280 fs/dcache.c:1195
 reconfigure_super+0x474/0x5b0 fs/super.c:1050
 do_remount fs/namespace.c:2892 [inline]
 path_mount+0x967/0xb30 fs/namespace.c:3671
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3875
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3875
 x64_sys_call+0x25c9/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:166
 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 0xffff888100443e40 of 4 bytes by task 24196 on cpu 1:
 __d_entry_type include/linux/dcache.h:397 [inline]
 d_is_symlink include/linux/dcache.h:427 [inline]
 step_into+0x12f/0x810 fs/namei.c:1847
 walk_component fs/namei.c:2010 [inline]
 link_path_walk+0x49d/0x810 fs/namei.c:2331
 path_lookupat+0x72/0x2b0 fs/namei.c:2492
 filename_lookup+0x127/0x300 fs/namei.c:2522
 user_path_at_empty+0x42/0x120 fs/namei.c:2929
 user_path_at include/linux/namei.h:58 [inline]
 do_faccessat+0x399/0x650 fs/open.c:490
 __do_sys_access fs/open.c:549 [inline]
 __se_sys_access fs/open.c:547 [inline]
 __x64_sys_access+0x37/0x40 fs/open.c:547
 x64_sys_call+0x2add/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:22
 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: 0x00200000 -> 0x00008000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24196 Comm: modprobe Not tainted 6.9.0-syzkaller-12277-g56fb6f92854f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/25 19:21 upstream 56fb6f92854f a10a183e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / step_into
2024/05/21 16:50 upstream 8f6a15f095a6 4c0d3ee3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / step_into
* Struck through repros no longer work on HEAD.