possible deadlock in mnt_want

possible deadlock in mnt_want_write
Status: upstream: reported syz repro on 2019/04/25 05:09
Reported-by: syzbot+662c18f543a2543ad297@syzkaller.appspotmail.com
First crash: 204d, last: 4d06h

similar bugs (3):
Kernel	Title	Repro	Count	Last	Reported	Patched	Status
upstream	possible deadlock in mnt_want_write	C	404	2d00h	480d	0/14	upstream: reported C repro on 2018/07/23 17:30
linux-4.19	possible deadlock in mnt_want_write	syz	30	4d03h	210d	0/1	upstream: reported syz repro on 2019/04/19 16:54
android-49	possible deadlock in mnt_want_write		1	462d	462d	0/3	auto-closed as invalid on 2019/02/22 14:57

Sample crash report:

IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready
audit: type=1804 audit(1561065156.704:39): pid=7163 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op="invalid_pcr" cause="open_writers" comm="syz-executor.0" name="/root/syzkaller-testdir296250821/syzkaller.0scJmJ/0/file0/file0" dev="sda1" ino=16497 res=1
======================================================
WARNING: possible circular locking dependency detected
4.14.128 #22 Not tainted
------------------------------------------------------
syz-executor.0/7163 is trying to acquire lock:
 (sb_writers#4){.+.+}, at: [<ffffffff81947c2f>] sb_start_write include/linux/fs.h:1548 [inline]
 (sb_writers#4){.+.+}, at: [<ffffffff81947c2f>] mnt_want_write+0x3f/0xb0 fs/namespace.c:386

but task is already holding lock:
 (&iint->mutex){+.+.}, at: [<ffffffff82ad1a4e>] process_measurement+0x2ae/0xb80 security/integrity/ima/ima_main.c:225

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&iint->mutex){+.+.}:
       lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xe8/0x1470 kernel/locking/mutex.c:893
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
       process_measurement+0x2ae/0xb80 security/integrity/ima/ima_main.c:225
       ima_file_check+0x30/0x40 security/integrity/ima/ima_main.c:353
       do_last fs/namei.c:3432 [inline]
       path_openat+0x1626/0x3f70 fs/namei.c:3566
       do_filp_open+0x18e/0x250 fs/namei.c:3600
       do_sys_open+0x2c5/0x430 fs/open.c:1065
       SYSC_open fs/open.c:1083 [inline]
       SyS_open+0x2d/0x40 fs/open.c:1078
       do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x42/0xb7

-> #0 (sb_writers#4){.+.+}:
       check_prev_add kernel/locking/lockdep.c:1901 [inline]
       check_prevs_add kernel/locking/lockdep.c:2018 [inline]
       validate_chain kernel/locking/lockdep.c:2460 [inline]
       __lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487
       lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
       percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
       percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
       __sb_start_write+0x1ae/0x2f0 fs/super.c:1363
       sb_start_write include/linux/fs.h:1548 [inline]
       mnt_want_write+0x3f/0xb0 fs/namespace.c:386
       ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:25
       ovl_open_maybe_copy_up+0xd5/0x130 fs/overlayfs/inode.c:341
       ovl_d_real+0xce/0x360 fs/overlayfs/super.c:88
       d_real include/linux/dcache.h:587 [inline]
       d_real include/linux/dcache.h:582 [inline]
       vfs_open+0x19e/0x220 fs/open.c:866
       dentry_open+0xac/0x220 fs/open.c:889
       ima_calc_file_hash+0x563/0x820 security/integrity/ima/ima_crypto.c:449
       ima_collect_measurement+0x3c1/0x450 security/integrity/ima/ima_api.c:227
       process_measurement+0x7dd/0xb80 security/integrity/ima/ima_main.c:264
       ima_file_check+0x30/0x40 security/integrity/ima/ima_main.c:353
       do_last fs/namei.c:3432 [inline]
       path_openat+0x1626/0x3f70 fs/namei.c:3566
       do_filp_open+0x18e/0x250 fs/namei.c:3600
       do_sys_open+0x2c5/0x430 fs/open.c:1065
       SYSC_open fs/open.c:1083 [inline]
       SyS_open+0x2d/0x40 fs/open.c:1078
       do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x42/0xb7

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&iint->mutex);
                               lock(sb_writers#4);
                               lock(&iint->mutex);
  lock(sb_writers#4);

 *** DEADLOCK ***

1 lock held by syz-executor.0/7163:
 #0:  (&iint->mutex){+.+.}, at: [<ffffffff82ad1a4e>] process_measurement+0x2ae/0xb80 security/integrity/ima/ima_main.c:225

stack backtrace:
CPU: 0 PID: 7163 Comm: syz-executor.0 Not tainted 4.14.128 #22
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x19c lib/dump_stack.c:53
 print_circular_bug.isra.0.cold+0x1cc/0x28f kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1901 [inline]
 check_prevs_add kernel/locking/lockdep.c:2018 [inline]
 validate_chain kernel/locking/lockdep.c:2460 [inline]
 __lock_acquire+0x2c89/0x45e0 kernel/locking/lockdep.c:3487
 lock_acquire+0x16f/0x430 kernel/locking/lockdep.c:3991
 percpu_down_read_preempt_disable include/linux/percpu-rwsem.h:36 [inline]
 percpu_down_read include/linux/percpu-rwsem.h:59 [inline]
 __sb_start_write+0x1ae/0x2f0 fs/super.c:1363
 sb_start_write include/linux/fs.h:1548 [inline]
 mnt_want_write+0x3f/0xb0 fs/namespace.c:386
 ovl_want_write+0x76/0xa0 fs/overlayfs/util.c:25
 ovl_open_maybe_copy_up+0xd5/0x130 fs/overlayfs/inode.c:341
 ovl_d_real+0xce/0x360 fs/overlayfs/super.c:88
 d_real include/linux/dcache.h:587 [inline]
 d_real include/linux/dcache.h:582 [inline]
 vfs_open+0x19e/0x220 fs/open.c:866
 dentry_open+0xac/0x220 fs/open.c:889
 ima_calc_file_hash+0x563/0x820 security/integrity/ima/ima_crypto.c:449
 ima_collect_measurement+0x3c1/0x450 security/integrity/ima/ima_api.c:227
 process_measurement+0x7dd/0xb80 security/integrity/ima/ima_main.c:264
 ima_file_check+0x30/0x40 security/integrity/ima/ima_main.c:353
 do_last fs/namei.c:3432 [inline]
 path_openat+0x1626/0x3f70 fs/namei.c:3566
 do_filp_open+0x18e/0x250 fs/namei.c:3600
 do_sys_open+0x2c5/0x430 fs/open.c:1065
 SYSC_open fs/open.c:1083 [inline]
 SyS_open+0x2d/0x40 fs/open.c:1078
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4592c9
RSP: 002b:00007ffe7131f048 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004592c9
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000020000200
RBP: 000000000075bf20 R08: 0000000000000000 R0

Crashes (16):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	Maintainers
ci2-linux-4-14	2019/06/20 21:19	linux-4.14.y	bb263a2a	34bf9440	.config	log	report	syz	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/08/10 18:44	linux-4.14.y	3ffe1e79	acb51638	.config	log	report	syz	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/08/08 20:48	linux-4.14.y	b19ffe6e	bcc419e9	.config	log	report	syz	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/06/28 07:05	linux-4.14.y	f4cc0ed9	7509bf36	.config	log	report	syz	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/06/26 18:46	linux-4.14.y	bc2bccef	4d342240	.config	log	report	syz	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/06/26 15:44	linux-4.14.y	bc2bccef	4d342240	.config	log	report	syz	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/06/25 14:27	linux-4.14.y	bc2bccef	0a8d1a96	.config	log	report	syz	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/04/25 04:09	linux-4.14.y	68d7a45e	8e3c52b1	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/11/11 12:35	linux-4.14.y	c9fda4f2	dc438b91	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/11/09 07:33	linux-4.14.y	c9fda4f2	1e35461e	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/10/20 04:33	linux-4.14.y	b98aebd2	8c88c9c1	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/09/30 04:11	linux-4.14.y	f6e27dbb	c1ad5441	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/08/10 17:59	linux-4.14.y	3ffe1e79	acb51638	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/08/08 20:04	linux-4.14.y	b19ffe6e	bcc419e9	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/08/03 17:16	linux-4.14.y	10d6aa56	6affd8e8	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-linux-4-14	2019/07/27 14:43	linux-4.14.y	ff33472c	c85e1c5b	.config	log	report		linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk