possible deadlock in mnt_want

possible deadlock in mnt_want_write (2)
Status: upstream: reported on 2021/06/15 16:59
Reported-by: syzbot+b42fe626038981fb7bfa@syzkaller.appspotmail.com
First crash: 48d, last: 14d

similar bugs (4):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	possible deadlock in mnt_want_write	C	done	done	662	294d	1102d	17/22	fixed on 2020/11/16 12:12
linux-4.19	possible deadlock in mnt_want_write	C			221	5d20h	832d	0/1	upstream: reported C repro on 2019/04/19 16:54
android-49	possible deadlock in mnt_want_write				1	1085d	1085d	0/3	auto-closed as invalid on 2019/02/22 14:57
linux-4.14	possible deadlock in mnt_want_write	C			4507	23d	827d	0/1	upstream: reported C repro on 2019/04/25 05:09

Sample crash report:

======================================================
WARNING: possible circular locking dependency detected
5.14.0-rc1-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.5/3922 is trying to acquire lock:
ffff888029f2a460 (sb_writers#5){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:375

but task is already holding lock:
ffff8880387923e0 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x75a/0x1ba0 security/integrity/ima/ima_main.c:253

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&iint->mutex){+.+.}-{3:3}:
       lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
       __mutex_lock_common+0x1ad/0x3770 kernel/locking/mutex.c:959
       __mutex_lock kernel/locking/mutex.c:1104 [inline]
       mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1119
       process_measurement+0x75a/0x1ba0 security/integrity/ima/ima_main.c:253
       ima_file_check+0xdb/0x130 security/integrity/ima/ima_main.c:499
       do_open fs/namei.c:3376 [inline]
       path_openat+0x284a/0x36b0 fs/namei.c:3507
       do_filp_open+0x253/0x4d0 fs/namei.c:3534
       do_sys_openat2+0x124/0x460 fs/open.c:1204
       do_sys_open fs/open.c:1220 [inline]
       __do_sys_openat fs/open.c:1236 [inline]
       __se_sys_openat fs/open.c:1231 [inline]
       __x64_sys_openat+0x243/0x290 fs/open.c:1231
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (sb_writers#5){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3051 [inline]
       check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174
       validate_chain kernel/locking/lockdep.c:3789 [inline]
       __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015
       lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1763 [inline]
       sb_start_write+0x4f/0x1a0 include/linux/fs.h:1833
       mnt_want_write+0x3b/0x80 fs/namespace.c:375
       ovl_maybe_copy_up+0x117/0x180 fs/overlayfs/copy_up.c:996
       ovl_open+0xa2/0x200 fs/overlayfs/file.c:149
       do_dentry_open+0x7cb/0x1020 fs/open.c:826
       vfs_open fs/open.c:949 [inline]
       dentry_open+0xc6/0x120 fs/open.c:965
       ima_calc_file_hash+0x157/0x1b00 security/integrity/ima/ima_crypto.c:557
       ima_collect_measurement+0x283/0x520 security/integrity/ima/ima_api.c:252
       process_measurement+0xf79/0x1ba0 security/integrity/ima/ima_main.c:330
       ima_file_check+0xdb/0x130 security/integrity/ima/ima_main.c:499
       do_open fs/namei.c:3376 [inline]
       path_openat+0x284a/0x36b0 fs/namei.c:3507
       do_filp_open+0x253/0x4d0 fs/namei.c:3534
       do_sys_openat2+0x124/0x460 fs/open.c:1204
       do_sys_open fs/open.c:1220 [inline]
       __do_sys_open fs/open.c:1228 [inline]
       __se_sys_open fs/open.c:1224 [inline]
       __x64_sys_open+0x221/0x270 fs/open.c:1224
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x44/0xae

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&iint->mutex);
                               lock(sb_writers#5);
                               lock(&iint->mutex);
  lock(sb_writers#5);

 *** DEADLOCK ***

1 lock held by syz-executor.5/3922:
 #0: ffff8880387923e0 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x75a/0x1ba0 security/integrity/ima/ima_main.c:253

stack backtrace:
CPU: 1 PID: 3922 Comm: syz-executor.5 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1ae/0x29f lib/dump_stack.c:105
 print_circular_bug+0xb17/0xdc0 kernel/locking/lockdep.c:2009
 check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2131
 check_prev_add kernel/locking/lockdep.c:3051 [inline]
 check_prevs_add+0x4f9/0x5b30 kernel/locking/lockdep.c:3174
 validate_chain kernel/locking/lockdep.c:3789 [inline]
 __lock_acquire+0x4476/0x6100 kernel/locking/lockdep.c:5015
 lock_acquire+0x182/0x4a0 kernel/locking/lockdep.c:5625
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1763 [inline]
 sb_start_write+0x4f/0x1a0 include/linux/fs.h:1833
 mnt_want_write+0x3b/0x80 fs/namespace.c:375
 ovl_maybe_copy_up+0x117/0x180 fs/overlayfs/copy_up.c:996
 ovl_open+0xa2/0x200 fs/overlayfs/file.c:149
 do_dentry_open+0x7cb/0x1020 fs/open.c:826
 vfs_open fs/open.c:949 [inline]
 dentry_open+0xc6/0x120 fs/open.c:965
 ima_calc_file_hash+0x157/0x1b00 security/integrity/ima/ima_crypto.c:557
 ima_collect_measurement+0x283/0x520 security/integrity/ima/ima_api.c:252
 process_measurement+0xf79/0x1ba0 security/integrity/ima/ima_main.c:330
 ima_file_check+0xdb/0x130 security/integrity/ima/ima_main.c:499
 do_open fs/namei.c:3376 [inline]
 path_openat+0x284a/0x36b0 fs/namei.c:3507
 do_filp_open+0x253/0x4d0 fs/namei.c:3534
 do_sys_openat2+0x124/0x460 fs/open.c:1204
 do_sys_open fs/open.c:1220 [inline]
 __do_sys_open fs/open.c:1228 [inline]
 __se_sys_open fs/open.c:1224 [inline]
 __x64_sys_open+0x221/0x270 fs/open.c:1224
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f28450b7188 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9
RDX: 0000000000000000 RSI: 0000000000002003 RDI: 0000000020000000
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffd1f48159f R14: 00007f28450b7300 R15: 0000000000022000

Crashes (8):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci-upstream-kasan-gce-smack-root	2021/07/16 02:19	upstream	dd9c7df94c1b	f115ae98	.config	log	report	info	possible deadlock in mnt_want_write
ci-upstream-kasan-gce-smack-root	2021/07/16 00:58	upstream	dd9c7df94c1b	f115ae98	.config	log	report	info	possible deadlock in mnt_want_write
ci-upstream-kasan-gce-smack-root	2021/07/15 04:40	upstream	8096acd7442e	b9a2f64e	.config	log	report	info	possible deadlock in mnt_want_write
ci-upstream-kasan-gce-smack-root	2021/07/13 16:18	upstream	7fef2edf7cc7	fa0594c3	.config	log	report	info	possible deadlock in mnt_want_write
ci-upstream-kasan-gce-smack-root	2021/07/12 22:27	upstream	7fef2edf7cc7	f415556d	.config	log	report	info	possible deadlock in mnt_want_write
ci-upstream-kasan-gce-smack-root	2021/07/11 20:13	upstream	98f7fdced2e0	8f5a7b8c	.config	log	report	info	possible deadlock in mnt_want_write
ci-upstream-kasan-gce-smack-root	2021/07/07 08:53	upstream	3dbdb38e2869	4846d5c1	.config	log	report	info	possible deadlock in mnt_want_write
ci-upstream-kasan-gce-smack-root	2021/06/11 16:55	upstream	06af8679449d	1ba81399	.config	log	report	info	possible deadlock in mnt_want_write