syzbot


KCSAN: data-race in __dentry_kill / step_into (9)

Status: moderation: reported on 2025/05/03 22:30
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+03eeb7a335f7bec13d0c@syzkaller.appspotmail.com
First crash: 13d, last: 1d23h
Similar bugs (8)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __dentry_kill / step_into (6) fs 1 395d 395d 0/28 auto-obsoleted due to no activity on 2024/05/21 11:40
upstream KCSAN: data-race in __dentry_kill / step_into (8) fs 23 85d 319d 0/28 auto-obsoleted due to no activity on 2025/04/17 06:32
upstream KCSAN: data-race in __dentry_kill / step_into fs 1 1680d 1680d 0/28 auto-closed as invalid on 2020/11/14 02:21
upstream KCSAN: data-race in __dentry_kill / step_into (5) fs 106 441d 526d 0/28 auto-obsoleted due to no activity on 2024/04/05 18:21
upstream KCSAN: data-race in __dentry_kill / step_into (4) fs 1 1175d 1175d 0/28 auto-closed as invalid on 2022/04/03 02:19
upstream KCSAN: data-race in __dentry_kill / step_into (7) fs 2 356d 360d 0/28 auto-obsoleted due to no activity on 2024/06/29 19:22
upstream KCSAN: data-race in __dentry_kill / step_into (2) fs 3 1435d 1473d 0/28 auto-closed as invalid on 2021/07/16 10:59
upstream KCSAN: data-race in __dentry_kill / step_into (3) fs 5 1237d 1295d 0/28 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 0xffff888106d7c240 of 4 bytes by task 3307 on cpu 0:
 dentry_unlist fs/dcache.c:605 [inline]
 __dentry_kill+0x230/0x4b0 fs/dcache.c:674
 dput+0x5e/0xd0 fs/dcache.c:902
 do_unlinkat+0x299/0x4c0 fs/namei.c:4646
 __do_sys_unlink fs/namei.c:4689 [inline]
 __se_sys_unlink fs/namei.c:4687 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:4687
 x64_sys_call+0x22a6/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106d7c240 of 4 bytes by task 3006 on cpu 1:
 __follow_mount_rcu fs/namei.c:1572 [inline]
 handle_mounts fs/namei.c:1623 [inline]
 step_into+0xe3/0x820 fs/namei.c:1976
 walk_component+0x162/0x220 fs/namei.c:2144
 lookup_last fs/namei.c:2636 [inline]
 path_lookupat+0xfe/0x2a0 fs/namei.c:2660
 filename_lookup+0x147/0x340 fs/namei.c:2689
 do_readlinkat+0x7d/0x320 fs/stat.c:568
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x2cf3/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00300008 -> 0x00004008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3006 Comm: udevd Not tainted 6.15.0-rc6-syzkaller-00085-gc94d59a126cb #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/15 05:48 upstream c94d59a126cb d6b2ee52 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __dentry_kill / step_into
2025/05/03 22:29 upstream 2a239ffbebb5 b0714e37 .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.