syzbot


KCSAN: data-race in __d_drop / dput (3)

Status: auto-closed as invalid on 2022/06/11 11:25
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 214d, last: 205d
similar bugs (3):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __d_drop / dput 1 325d 325d 0/24 auto-closed as invalid on 2022/02/10 17:36
upstream KCSAN: data-race in __d_drop / dput (2) 1 289d 289d 0/24 auto-closed as invalid on 2022/03/19 02:06
upstream KCSAN: data-race in __d_drop / dput (4) 1 99d 99d 0/24 auto-closed as invalid on 2022/09/25 01:35

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __d_drop / dput

write to 0xffff888120b170d0 of 8 bytes by task 8756 on cpu 1:
 __d_drop+0x16a/0x240 fs/dcache.c:508
 __dentry_kill+0x12f/0x450 fs/dcache.c:602
 shrink_dentry_list+0x20f/0x380 fs/dcache.c:1201
 shrink_dcache_sb+0x188/0x2d0 fs/dcache.c:1321
 reconfigure_super+0x146/0x540 fs/super.c:888
 do_remount fs/namespace.c:2702 [inline]
 path_mount+0x984/0xb60 fs/namespace.c:3362
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount+0x281/0x2d0 fs/namespace.c:3568
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3568
 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+0x44/0xae

read to 0xffff888120b170d0 of 8 bytes by task 1817 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:332 [inline]
 fast_dput fs/dcache.c:837 [inline]
 dput+0xa4/0x1f0 fs/dcache.c:900
 path_put+0x1b/0x30 fs/namei.c:557
 vfs_statx+0x33a/0x3d0 fs/stat.c:238
 vfs_fstatat fs/stat.c:255 [inline]
 vfs_lstat include/linux/fs.h:3147 [inline]
 __do_sys_newlstat fs/stat.c:411 [inline]
 __se_sys_newlstat+0x6a/0x270 fs/stat.c:405
 __x64_sys_newlstat+0x2d/0x40 fs/stat.c:405
 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+0x44/0xae

value changed: 0xffff888237751378 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1817 Comm: syz-executor.2 Not tainted 5.18.0-rc5-syzkaller-00163-g4b97bac0756a-dirty #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 2022/05/07 11:19 upstream 4b97bac0756a e60b1103 .config log report info KCSAN: data-race in __d_drop / dput
ci2-upstream-kcsan-gce 2022/04/28 14:32 upstream 8f4dd16603ce 8a1f1f07 .config log report info KCSAN: data-race in __d_drop / dput
* Struck through repros no longer work on HEAD.