syzbot


KCSAN: data-race in lookup_fast / retain_dentry

Status: auto-closed as invalid on 2020/09/23 11:25
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 787d, last: 775d
similar bugs (4):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in lookup_fast / retain_dentry (4) 4 591d 642d 0/24 auto-closed as invalid on 2021/03/27 05:59
upstream KCSAN: data-race in lookup_fast / retain_dentry (5) 1 542d 542d 0/24 auto-closed as invalid on 2021/05/17 09:51
upstream KCSAN: data-race in lookup_fast / retain_dentry (2) 1 737d 737d 0/24 auto-closed as invalid on 2020/10/31 17:53
upstream KCSAN: data-race in lookup_fast / retain_dentry (3) 2 681d 665d 0/24 auto-closed as invalid on 2020/12/27 03:33

Sample crash report:
==================================================================
BUG: KCSAN: data-race in lookup_fast / retain_dentry

write to 0xffff8880658d49c0 of 4 bytes by task 29483 on cpu 0:
 retain_dentry+0x1db/0x260 fs/dcache.c:659
 dput+0x10e/0x420 fs/dcache.c:873
 __fput+0x398/0x4d0 fs/file_table.c:294
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:141
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:139 [inline]
 exit_to_user_mode_prepare+0x1b2/0x210 kernel/entry/common.c:166
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:241
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880658d49c0 of 4 bytes by task 29489 on cpu 1:
 d_revalidate fs/namei.c:767 [inline]
 lookup_fast+0x15f/0x370 fs/namei.c:1493
 walk_component+0x5c/0x350 fs/namei.c:1856
 lookup_last fs/namei.c:2309 [inline]
 path_lookupat+0x12d/0x560 fs/namei.c:2333
 filename_lookup+0xf2/0x380 fs/namei.c:2366
 user_path_at_empty+0x3b/0x50 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 do_mount fs/namespace.c:3202 [inline]
 __do_sys_mount fs/namespace.c:3413 [inline]
 __se_sys_mount+0xf1/0x180 fs/namespace.c:3390
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3390
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29489 Comm: syz-executor.1 Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2020/08/19 11:20 upstream 18445bf405cb e1c29030 .config log report
ci2-upstream-kcsan-gce 2020/08/07 14:34 upstream 86cfccb66937 28ac5c9e .config log report
* Struck through repros no longer work on HEAD.