syzbot


KCSAN: data-race in __d_lookup_rcu / __d_rehash (7)

Status: auto-obsoleted due to no activity on 2024/04/05 04:37
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+e2f256d639284c733c14@syzkaller.appspotmail.com
First crash: 85d, last: 85d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash fs 1 1576d 1576d 0/26 auto-closed as invalid on 2020/04/10 19:18
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (2) fs 1 880d 880d 0/26 auto-closed as invalid on 2022/01/31 01:45
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (6) ext4 1 187d 186d 0/26 auto-obsoleted due to no activity on 2023/12/25 18:18
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (3) ext4 3 766d 742d 0/26 auto-closed as invalid on 2022/05/28 02:05
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (5) fs 1 451d 451d 0/26 auto-obsoleted due to no activity on 2023/04/05 19:44
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (4) fs 1 611d 610d 0/26 auto-obsoleted due to no activity on 2022/10/27 12:04

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __d_lookup_rcu / __d_rehash

read to 0xffff8881636eb850 of 8 bytes by task 6795 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:342 [inline]
 __d_lookup_rcu+0x120/0x290 fs/dcache.c:2224
 lookup_fast+0x8e/0x290 fs/namei.c:1628
 walk_component+0x3f/0x230 fs/namei.c:2001
 lookup_last fs/namei.c:2462 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2486
 filename_lookup+0x126/0x300 fs/namei.c:2515
 vfs_statx+0xa2/0x320 fs/stat.c:244
 vfs_fstatat+0xcd/0x100 fs/stat.c:304
 __do_sys_newfstatat fs/stat.c:468 [inline]
 __se_sys_newfstatat+0x58/0x260 fs/stat.c:462
 __x64_sys_newfstatat+0x55/0x60 fs/stat.c:462
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

write to 0xffff8881636eb850 of 8 bytes by task 2774 on cpu 1:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xc4/0x220 fs/dcache.c:2403
 __d_add+0x36d/0x4a0 fs/dcache.c:2618
 d_add+0x45/0x50 fs/dcache.c:2641
 simple_lookup+0x89/0xa0 fs/libfs.c:79
 lookup_one_qstr_excl+0xc0/0x180 fs/namei.c:1608
 do_unlinkat+0x144/0x4c0 fs/namei.c:4390
 __do_sys_unlink fs/namei.c:4450 [inline]
 __se_sys_unlink fs/namei.c:4448 [inline]
 __x64_sys_unlink+0x30/0x40 fs/namei.c:4448
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 2774 Comm: udevd Not tainted 6.8.0-rc6-syzkaller-00120-g87adedeba51a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/03/01 04:36 upstream 87adedeba51a 352ab904 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __d_lookup_rcu / __d_rehash
* Struck through repros no longer work on HEAD.