syzbot


KCSAN: data-race in lookup_fast / shrink_dentry_list

Status: auto-closed as invalid on 2020/10/08 14:19
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 780d, last: 754d
similar bugs (6):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in lookup_fast / shrink_dentry_list (6) 1 75d 75d 0/24 auto-closed as invalid on 2022/08/18 12:57
upstream KCSAN: data-race in lookup_fast / shrink_dentry_list (4) 1 546d 546d 0/24 auto-closed as invalid on 2021/05/04 09:30
upstream KCSAN: data-race in lookup_fast / shrink_dentry_list (2) 1 696d 696d 0/24 auto-closed as invalid on 2020/12/05 11:21
upstream KCSAN: data-race in lookup_fast / shrink_dentry_list (3) 2 603d 632d 0/24 auto-closed as invalid on 2021/03/08 10:39
upstream KCSAN: data-race in lookup_fast / shrink_dentry_list (7) 1 38d 38d 0/24 auto-closed as invalid on 2022/09/24 23:48
upstream KCSAN: data-race in lookup_fast / shrink_dentry_list (5) 1 396d 396d 0/24 auto-closed as invalid on 2021/10/01 10:16

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

write to 0xffff88811ec77240 of 4 bytes by task 1588 on cpu 1:
 shrink_dentry_list+0x127/0x530 fs/dcache.c:421
 shrink_dcache_sb+0x10d/0x1c0 fs/dcache.c:1261
 reconfigure_super+0x267/0x4d0 fs/super.c:940
 do_remount fs/namespace.c:2612 [inline]
 path_mount+0x13c2/0x1c70 fs/namespace.c:3184
 do_mount fs/namespace.c:3205 [inline]
 __do_sys_mount fs/namespace.c:3413 [inline]
 __se_sys_mount+0x126/0x180 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

read to 0xffff88811ec77240 of 4 bytes by task 8729 on cpu 0:
 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]
 vfs_statx+0xb8/0x2b0 fs/stat.c:202
 vfs_lstat include/linux/fs.h:3178 [inline]
 __do_sys_newlstat fs/stat.c:374 [inline]
 __se_sys_newlstat+0x46/0x250 fs/stat.c:368
 __x64_sys_newlstat+0x2d/0x40 fs/stat.c:368
 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: 0 PID: 8729 Comm: syz-executor.5 Not tainted 5.9.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2020/09/03 14:17 upstream fc3abb53250a abf9ba4f .config log report
ci2-upstream-kcsan-gce 2020/08/27 02:49 upstream 15bc20c6af4c 318430cb .config log report
ci2-upstream-kcsan-gce 2020/08/08 21:45 upstream 449dc8c97089 01975a06 .config log report
* Struck through repros no longer work on HEAD.