syzbot


possible deadlock in ovl_copy_up_start (4)

Status: upstream: reported on 2023/02/03 17:59
Reported-by: syzbot+6871a01d6aef10244d74@syzkaller.appspotmail.com
First crash: 474d, last: 474d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ovl_copy_up_start (3) overlayfs 1 48d 44d 0/26 closed as dup on 2024/04/08 10:02
linux-4.14 possible deadlock in ovl_copy_up_start (2) 6 856d 906d 0/1 auto-closed as invalid on 2022/05/17 06:42
upstream possible deadlock in ovl_copy_up_start (2) overlayfs 1 240d 236d 0/26 closed as dup on 2023/10/04 08:46
linux-4.14 possible deadlock in ovl_copy_up_start (3) 2 644d 671d 0/1 auto-obsoleted due to no activity on 2022/12/14 20:28
linux-4.14 possible deadlock in ovl_copy_up_start 9 1117d 1325d 0/1 auto-closed as invalid on 2021/08/29 09:58
upstream possible deadlock in ovl_copy_up_start overlayfs 2 2035d 2043d 11/26 fixed on 2018/11/12 21:25

Sample crash report:
======================================================
WARNING: possible circular locking dependency detected
4.14.304-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/13215 is trying to acquire lock:
 (&oi->lock){+.+.}, at: [<ffffffff82317c30>] ovl_copy_up_start+0x40/0xe0 fs/overlayfs/util.c:318

but task is already holding lock:
 (sb_writers#6){.+.+}, at: [<ffffffff818e1d0a>] sb_start_write include/linux/fs.h:1551 [inline]
 (sb_writers#6){.+.+}, at: [<ffffffff818e1d0a>] mnt_want_write+0x3a/0xb0 fs/namespace.c:386

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#6){.+.+}:
       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+0x64/0x260 fs/super.c:1342
       sb_start_write include/linux/fs.h:1551 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:386
       ovl_create_object+0x75/0x1d0 fs/overlayfs/dir.c:538
       lookup_open+0x77a/0x1750 fs/namei.c:3241
       do_last fs/namei.c:3334 [inline]
       path_openat+0xe08/0x2970 fs/namei.c:3571
       do_filp_open+0x179/0x3c0 fs/namei.c:3605
       do_sys_open+0x296/0x410 fs/open.c:1081
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x5e/0xd3

-> #1 (&ovl_i_mutex_dir_key[depth]){++++}:
       down_read+0x36/0x80 kernel/locking/rwsem.c:24
       inode_lock_shared include/linux/fs.h:729 [inline]
       lookup_slow+0x129/0x400 fs/namei.c:1674
       lookup_one_len_unlocked+0x3a0/0x410 fs/namei.c:2595
       ovl_lower_positive+0x184/0x350 fs/overlayfs/namei.c:783
       ovl_rename+0x47c/0xe50 fs/overlayfs/dir.c:968
       vfs_rename+0x560/0x1820 fs/namei.c:4498
       SYSC_renameat2 fs/namei.c:4646 [inline]
       SyS_renameat2+0x95b/0xad0 fs/namei.c:4535
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x5e/0xd3

-> #0 (&oi->lock){+.+.}:
       lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
       __mutex_lock_common kernel/locking/mutex.c:756 [inline]
       __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
       ovl_copy_up_start+0x40/0xe0 fs/overlayfs/util.c:318
       ovl_copy_up_one+0x21f/0x910 fs/overlayfs/copy_up.c:631
       ovl_copy_up_flags+0xd5/0x120 fs/overlayfs/copy_up.c:686
       ovl_setattr fs/overlayfs/inode.c:42 [inline]
       ovl_setattr+0x66/0x500 fs/overlayfs/inode.c:19
       notify_change+0x56b/0xd10 fs/attr.c:315
       chown_common+0x40b/0x4b0 fs/open.c:631
       SYSC_fchownat fs/open.c:661 [inline]
       SyS_fchownat+0xf6/0x190 fs/open.c:641
       do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
       entry_SYSCALL_64_after_hwframe+0x5e/0xd3

other info that might help us debug this:

Chain exists of:
  &oi->lock --> &ovl_i_mutex_dir_key[depth] --> sb_writers#6

 Possible unsafe locking scenario:

       CPU0                    CPU1
hub 9-0:1.0: USB hub found
       ----                    ----
  lock(sb_writers#6);
                               lock(&ovl_i_mutex_dir_key[depth]);
                               lock(sb_writers#6);
  lock(&oi->lock);

 *** DEADLOCK ***

3 locks held by syz-executor.1/13215:
 #0:  (sb_writers#19){.+.+}, at: [<ffffffff818e1d0a>] sb_start_write include/linux/fs.h:1551 [inline]
 #0:  (sb_writers#19){.+.+}, at: [<ffffffff818e1d0a>] mnt_want_write+0x3a/0xb0 fs/namespace.c:386
 #1: 
hub 9-0:1.0: 8 ports detected
 (&ovl_i_mutex_key[depth]#2){+.+.}, at: [<ffffffff81865982>] inode_lock include/linux/fs.h:719 [inline]
 (&ovl_i_mutex_key[depth]#2){+.+.}, at: [<ffffffff81865982>] chown_common+0x272/0x4b0 fs/open.c:628
 #2:  (sb_writers#6){.+.+}, at: [<ffffffff818e1d0a>] sb_start_write include/linux/fs.h:1551 [inline]
 #2:  (sb_writers#6){.+.+}, at: [<ffffffff818e1d0a>] mnt_want_write+0x3a/0xb0 fs/namespace.c:386

stack backtrace:
CPU: 1 PID: 13215 Comm: syz-executor.1 Not tainted 4.14.304-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258
 check_prev_add kernel/locking/lockdep.c:1905 [inline]
 check_prevs_add kernel/locking/lockdep.c:2022 [inline]
 validate_chain kernel/locking/lockdep.c:2464 [inline]
 __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491
 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998
 __mutex_lock_common kernel/locking/mutex.c:756 [inline]
 __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893
 ovl_copy_up_start+0x40/0xe0 fs/overlayfs/util.c:318
 ovl_copy_up_one+0x21f/0x910 fs/overlayfs/copy_up.c:631
 ovl_copy_up_flags+0xd5/0x120 fs/overlayfs/copy_up.c:686
hub 9-0:1.0: USB hub found
 ovl_setattr fs/overlayfs/inode.c:42 [inline]
 ovl_setattr+0x66/0x500 fs/overlayfs/inode.c:19
 notify_change+0x56b/0xd10 fs/attr.c:315
hub 9-0:1.0: 8 ports detected
 chown_common+0x40b/0x4b0 fs/open.c:631
 SYSC_fchownat fs/open.c:661 [inline]
 SyS_fchownat+0xf6/0x190 fs/open.c:641
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3
RIP: 0033:0x7f3f50d530c9
RSP: 002b:00007f3f4f2c5168 EFLAGS: 00000246 ORIG_RAX: 000000000000005e
RAX: ffffffffffffffda RBX: 00007f3f50e72f80 RCX: 00007f3f50d530c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000480
RBP: 00007f3f50daeae9 R08: 0000000000000000 R09: 0000000000000000
hub 9-0:1.0: USB hub found
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc6ebf730f R14: 00007f3f4f2c5300 R15: 0000000000022000
hub 9-0:1.0: 8 ports detected
overlayfs: failed to create directory ./file1/work (errno: 1); mounting read-only
overlayfs: failed to create directory ./file1/work (errno: 1); mounting read-only
overlayfs: failed to create directory ./file1/work (errno: 1); mounting read-only
overlayfs: failed to create directory ./file1/work (errno: 1); mounting read-only
overlayfs: failed to create directory ./file1/work (errno: 1); mounting read-only
overlayfs: failed to create directory ./file1/work (errno: 1); mounting read-only
overlayfs: failed to create directory ./file1/work (errno: 1); mounting read-only
PF_BRIDGE: br_mdb_parse() with invalid attr
kauditd_printk_skb: 38 callbacks suppressed
audit: type=1800 audit(1675447150.329:139): pid=13454 uid=0 auid=4294967295 ses=4294967295 op="collect_data" cause="failed(directio)" comm="syz-executor.5" name="file0" dev="sda1" ino=14387 res=0
caif:caif_disconnect_client(): nothing to disconnect
netlink: 284 bytes leftover after parsing attributes in process `syz-executor.1'.
team0 (unregistering): Port device team_slave_0 removed
team0 (unregistering): Port device team_slave_1 removed
netlink: 284 bytes leftover after parsing attributes in process `syz-executor.1'.
netlink: 284 bytes leftover after parsing attributes in process `syz-executor.1'.

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/02/03 17:59 linux-4.14.y 3949d1610004 1b2f701a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-4-14 possible deadlock in ovl_copy_up_start
* Struck through repros no longer work on HEAD.