syzbot


KCSAN: data-race in __d_lookup_rcu / __d_rehash (4)

Status: auto-obsoleted due to no activity on 2022/10/27 12:04
Reported-by: syzbot+f8ea0aa0e0fbd5005320@syzkaller.appspotmail.com
First crash: 73d, last: 73d
similar bugs (3):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash 1 1037d 1037d 0/24 auto-closed as invalid on 2020/04/10 19:18
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (2) 1 342d 342d 0/24 auto-closed as invalid on 2022/01/31 01:45
upstream KCSAN: data-race in __d_lookup_rcu / __d_rehash (3) 3 228d 204d 0/24 auto-closed as invalid on 2022/05/28 02:05

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

read to 0xffff8881060d0b50 of 8 bytes by task 8270 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:334 [inline]
 __d_lookup_rcu+0x12e/0x2a0 fs/dcache.c:2400
 lookup_fast+0x8a/0x270 fs/namei.c:1620
 walk_component fs/namei.c:1989 [inline]
 link_path_walk+0x439/0x8a0 fs/namei.c:2320
 path_openat+0x19c/0x1b00 fs/namei.c:3687
 do_filp_open+0x105/0x220 fs/namei.c:3718
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1313
 do_sys_open fs/open.c:1329 [inline]
 __do_sys_openat fs/open.c:1345 [inline]
 __se_sys_openat fs/open.c:1340 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1340
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff8881060d0b50 of 8 bytes by task 8610 on cpu 1:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0xb9/0x1f0 fs/dcache.c:2579
 __d_add+0x36d/0x4a0 fs/dcache.c:2803
 d_add+0x41/0x50 fs/dcache.c:2826
 simple_lookup+0x85/0x90 fs/libfs.c:75
 __lookup_hash+0xbc/0x180 fs/namei.c:1601
 do_unlinkat+0x14b/0x510 fs/namei.c:4281
 __do_sys_unlink fs/namei.c:4345 [inline]
 __se_sys_unlink fs/namei.c:4343 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:4343
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8610 Comm: udevd Not tainted 6.0.0-rc6-syzkaller-00045-gdc164f4fb00a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2022/09/22 12:04 upstream dc164f4fb00a 60af5050 .config log report info KCSAN: data-race in __d_lookup_rcu / __d_rehash
* Struck through repros no longer work on HEAD.