syzbot


KCSAN: data-race in __dentry_kill / step_into (8)

Status: moderation: reported on 2024/07/01 14:35
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+8cbdf86ac3f842471303@syzkaller.appspotmail.com
First crash: 2d23h, last: 2d23h
Similar bugs (7)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __dentry_kill / step_into (6) fs 1 79d 79d 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 1363d 1363d 0/27 auto-closed as invalid on 2020/11/14 02:21
upstream KCSAN: data-race in __dentry_kill / step_into (5) fs 106 124d 209d 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 858d 858d 0/27 auto-closed as invalid on 2022/04/03 02:19
upstream KCSAN: data-race in __dentry_kill / step_into (7) fs 2 39d 43d 0/27 auto-obsoleted due to no activity on 2024/06/29 19:22
upstream KCSAN: data-race in __dentry_kill / step_into (2) fs 3 1119d 1156d 0/27 auto-closed as invalid on 2021/07/16 10:59
upstream KCSAN: data-race in __dentry_kill / step_into (3) fs 5 921d 978d 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 0xffff88810642e840 of 4 bytes by task 3065 on cpu 1:
 dentry_unlist fs/dcache.c:548 [inline]
 __dentry_kill+0x228/0x4b0 fs/dcache.c:617
 dput+0x5c/0xd0 fs/dcache.c:845
 do_unlinkat+0x257/0x4c0 fs/namei.c:4410
 __do_sys_unlink fs/namei.c:4455 [inline]
 __se_sys_unlink fs/namei.c:4453 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4453
 x64_sys_call+0x28a3/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:88
 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 0xffff88810642e840 of 4 bytes by task 2784 on cpu 0:
 __follow_mount_rcu fs/namei.c:1485 [inline]
 handle_mounts fs/namei.c:1536 [inline]
 step_into+0xe7/0x810 fs/namei.c:1842
 walk_component+0x169/0x230 fs/namei.c:2010
 lookup_last fs/namei.c:2469 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2493
 filename_lookup+0x127/0x300 fs/namei.c:2522
 user_path_at_empty+0x42/0x120 fs/namei.c:2929
 do_readlinkat+0x92/0x210 fs/stat.c:499
 __do_sys_readlink fs/stat.c:532 [inline]
 __se_sys_readlink fs/stat.c:529 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:529
 x64_sys_call+0x264b/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:90
 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: 0x00600008 -> 0x00008008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2784 Comm: udevd 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 14:35 upstream 22a40d14b572 b294e901 .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.