possible deadlock in ovl_maybe_copy

possible deadlock in ovl_maybe_copy_up
Status: upstream: reported on 2020/11/23 10:05
Reported-by: syzbot+c18f2f6a7b08c51e3025@syzkaller.appspotmail.com
First crash: 63d, last: 21d

Sample crash report:

======================================================
WARNING: possible circular locking dependency detected
5.11.0-rc1-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/30642 is trying to acquire lock:
ffff888021eae460 (sb_writers#4){.+.+}-{0:0}, at: ovl_maybe_copy_up+0x11f/0x190 fs/overlayfs/copy_up.c:994

but task is already holding lock:
ffff8880115e1f20 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x363/0x1760 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}:
       __mutex_lock_common kernel/locking/mutex.c:956 [inline]
       __mutex_lock+0x134/0x1110 kernel/locking/mutex.c:1103
       process_measurement+0x363/0x1760 security/integrity/ima/ima_main.c:253
       ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:498
       do_open fs/namei.c:3256 [inline]
       path_openat+0x154d/0x2730 fs/namei.c:3371
       do_filp_open+0x17e/0x3c0 fs/namei.c:3398
       do_sys_openat2+0x16d/0x420 fs/open.c:1172
       do_sys_open fs/open.c:1188 [inline]
       __do_sys_openat fs/open.c:1204 [inline]
       __se_sys_openat fs/open.c:1199 [inline]
       __x64_sys_openat+0x13f/0x1f0 fs/open.c:1199
       do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9

-> #0 (sb_writers#4){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:2868 [inline]
       check_prevs_add kernel/locking/lockdep.c:2993 [inline]
       validate_chain kernel/locking/lockdep.c:3608 [inline]
       __lock_acquire+0x2ade/0x5500 kernel/locking/lockdep.c:4832
       lock_acquire kernel/locking/lockdep.c:5437 [inline]
       lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1592 [inline]
       sb_start_write include/linux/fs.h:1662 [inline]
       mnt_want_write+0x69/0x3d0 fs/namespace.c:354
       ovl_maybe_copy_up+0x11f/0x190 fs/overlayfs/copy_up.c:994
       ovl_open+0xba/0x270 fs/overlayfs/file.c:149
       do_dentry_open+0x4b9/0x11b0 fs/open.c:817
       vfs_open fs/open.c:931 [inline]
       dentry_open+0x132/0x1d0 fs/open.c:947
       ima_calc_file_hash+0x2d2/0x4b0 security/integrity/ima/ima_crypto.c:557
       ima_collect_measurement+0x4ca/0x570 security/integrity/ima/ima_api.c:250
       process_measurement+0xca6/0x1760 security/integrity/ima/ima_main.c:330
       ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:498
       do_open fs/namei.c:3256 [inline]
       path_openat+0x154d/0x2730 fs/namei.c:3371
       do_filp_open+0x17e/0x3c0 fs/namei.c:3398
       do_sys_openat2+0x16d/0x420 fs/open.c:1172
       do_sys_open fs/open.c:1188 [inline]
       __do_sys_open fs/open.c:1196 [inline]
       __se_sys_open fs/open.c:1192 [inline]
       __x64_sys_open+0x119/0x1c0 fs/open.c:1192
       do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
       entry_SYSCALL_64_after_hwframe+0x44/0xa9

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.0/30642:
 #0: ffff8880115e1f20 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x363/0x1760 security/integrity/ima/ima_main.c:253

stack backtrace:
CPU: 0 PID: 30642 Comm: syz-executor.0 Not tainted 5.11.0-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:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2117
 check_prev_add kernel/locking/lockdep.c:2868 [inline]
 check_prevs_add kernel/locking/lockdep.c:2993 [inline]
 validate_chain kernel/locking/lockdep.c:3608 [inline]
 __lock_acquire+0x2ade/0x5500 kernel/locking/lockdep.c:4832
 lock_acquire kernel/locking/lockdep.c:5437 [inline]
 lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1592 [inline]
 sb_start_write include/linux/fs.h:1662 [inline]
 mnt_want_write+0x69/0x3d0 fs/namespace.c:354
 ovl_maybe_copy_up+0x11f/0x190 fs/overlayfs/copy_up.c:994
 ovl_open+0xba/0x270 fs/overlayfs/file.c:149
 do_dentry_open+0x4b9/0x11b0 fs/open.c:817
 vfs_open fs/open.c:931 [inline]
 dentry_open+0x132/0x1d0 fs/open.c:947
 ima_calc_file_hash+0x2d2/0x4b0 security/integrity/ima/ima_crypto.c:557
 ima_collect_measurement+0x4ca/0x570 security/integrity/ima/ima_api.c:250
 process_measurement+0xca6/0x1760 security/integrity/ima/ima_main.c:330
 ima_file_check+0xb9/0x100 security/integrity/ima/ima_main.c:498
 do_open fs/namei.c:3256 [inline]
 path_openat+0x154d/0x2730 fs/namei.c:3371
 do_filp_open+0x17e/0x3c0 fs/namei.c:3398
 do_sys_openat2+0x16d/0x420 fs/open.c:1172
 do_sys_open fs/open.c:1188 [inline]
 __do_sys_open fs/open.c:1196 [inline]
 __se_sys_open fs/open.c:1192 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1192
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45e219
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f91522f3c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045e219
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000020000040
RBP: 000000000119bfc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c
R13: 00007ffc4400d0bf R14: 00007f91522f49c0 R15: 000000000119bf8c

Crashes (10):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci-upstream-kasan-gce-root	2021/01/03 14:41	upstream	3516bd72	79264ae3	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-kasan-gce-selinux-root	2020/11/22 09:45	upstream	a349e4c6	0d27f508	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-kasan-gce-root	2020/11/22 09:40	upstream	a349e4c6	0d27f508	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-linux-next-kasan-gce-root	2020/11/29 02:51	linux-next	6174f052	a0092f9d	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-linux-next-kasan-gce-root	2020/11/29 01:00	linux-next	6174f052	a0092f9d	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-linux-next-kasan-gce-root	2020/11/27 19:10	linux-next	6174f052	486f93ef	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-linux-next-kasan-gce-root	2020/11/27 17:41	linux-next	6174f052	486f93ef	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-linux-next-kasan-gce-root	2020/11/26 14:37	linux-next	6147c83f	1d2b823e	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-linux-next-kasan-gce-root	2020/11/26 10:44	linux-next	6147c83f	2f1cec62	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu
ci-upstream-linux-next-kasan-gce-root	2020/11/22 09:40	linux-next	95065cb5	0d27f508	.config	log	report	info	linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu