syzbot


KCSAN: data-race in get_mountpoint / shrink_dentry_list

Status: auto-closed as invalid on 2022/05/13 05:58
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 235d, last: 235d

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

read-write to 0xffff8881365296c0 of 4 bytes by task 8698 on cpu 0:
 d_shrink_del fs/dcache.c:448 [inline]
 shrink_dentry_list+0x1cf/0x380 fs/dcache.c:1188
 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 0xffff8881365296c0 of 4 bytes by task 8709 on cpu 1:
 d_mountpoint include/linux/dcache.h:377 [inline]
 get_mountpoint+0x16/0x300 fs/namespace.c:781
 lock_mount+0x82/0x1c0 fs/namespace.c:2300
 do_loopback+0x162/0x2d0 fs/namespace.c:2436
 path_mount+0x3e8/0xb60 fs/namespace.c:3364
 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

value changed: 0x00280400 -> 0x00200000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8709 Comm: syz-executor.2 Not tainted 5.18.0-rc1-syzkaller-00037-g42e7a03d3bad-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs (sda1): can't enable nombcache during remount

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2022/04/08 05:57 upstream 42e7a03d3bad c6ff3e05 .config log report info KCSAN: data-race in get_mountpoint / shrink_dentry_list
* Struck through repros no longer work on HEAD.