possible deadlock in ovl_copy_up_start (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3949d1610004 Linux 4.14.304
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12a3be73480000
kernel config: https://syzkaller.appspot.com/x/.config?x=db4418ccbf710113
dashboard link: https://syzkaller.appspot.com/bug?extid=6871a01d6aef10244d74
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2230a6d7e7f4/disk-3949d161.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9b8d5667f298/vmlinux-3949d161.xz
kernel image: https://storage.googleapis.com/syzbot-assets/825468a3e783/bzImage-3949d161.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6871a0...@syzkaller.appspotmail.com

======================================================
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'.


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