[syzbot] possible deadlock in filename_create

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f141df371335 Merge tag 'audit-pr-20221107' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11802789880000
kernel config: https://syzkaller.appspot.com/x/.config?x=771b06c41e08f95b
dashboard link: https://syzkaller.appspot.com/bug?extid=95cb07e3840546a4827b
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/25bd3ddd1720/disk-f141df37.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e2a12f518443/vmlinux-f141df37.xz
kernel image: https://storage.googleapis.com/syzbot-assets/09ba7134ea9d/bzImage-f141df37.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+95cb07...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc4-syzkaller-00015-gf141df371335 #0 Not tainted
------------------------------------------------------
syz-executor.3/25735 is trying to acquire lock:
ffff88807a8a8090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff8880361c0980 (&type->i_mutex_dir_key#19/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
ffff8880361c0980 (&type->i_mutex_dir_key#19/1){+.+.}-{3:3}, at: filename_create+0x22a/0x4f0 fs/namei.c:3806

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&type->i_mutex_dir_key#19/1){+.+.}-{3:3}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
down_write_nested+0xa2/0x280 kernel/locking/rwsem.c:1672
inode_lock_nested include/linux/fs.h:791 [inline]
filename_create+0x22a/0x4f0 fs/namei.c:3806
do_symlinkat+0xe4/0x600 fs/namei.c:4419
__do_sys_symlinkat fs/namei.c:4446 [inline]
__se_sys_symlinkat fs/namei.c:4443 [inline]
__x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4443
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+0x63/0xcd

-> #1 (sb_writers#28){.+.+}-{0:0}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1826 [inline]
sb_start_write+0x4d/0x1a0 include/linux/fs.h:1901
mnt_want_write_file+0x5a/0x1f0 fs/namespace.c:437
reiserfs_ioctl+0x16e/0x340 fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
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+0x63/0xcd

-> #0 (&sbi->lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__mutex_lock_common+0x1bd/0x26e0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x147/0x490 fs/reiserfs/namei.c:364
__lookup_hash+0x115/0x240 fs/namei.c:1601
filename_create+0x25f/0x4f0 fs/namei.c:3807
do_symlinkat+0xe4/0x600 fs/namei.c:4419
__do_sys_symlinkat fs/namei.c:4446 [inline]
__se_sys_symlinkat fs/namei.c:4443 [inline]
__x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4443
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+0x63/0xcd

other info that might help us debug this:

Chain exists of:
&sbi->lock --> sb_writers#28 --> &type->i_mutex_dir_key#19/1

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&type->i_mutex_dir_key#19/1);
lock(sb_writers#28);
lock(&type->i_mutex_dir_key#19/1);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor.3/25735:
#0: ffff888075a1e460 (sb_writers#28){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393
#1: ffff8880361c0980 (&type->i_mutex_dir_key#19/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline]
#1: ffff8880361c0980 (&type->i_mutex_dir_key#19/1){+.+.}-{3:3}, at: filename_create+0x22a/0x4f0 fs/namei.c:3806

stack backtrace:
CPU: 0 PID: 25735 Comm: syz-executor.3 Not tainted 6.1.0-rc4-syzkaller-00015-gf141df371335 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__mutex_lock_common+0x1bd/0x26e0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x147/0x490 fs/reiserfs/namei.c:364
__lookup_hash+0x115/0x240 fs/namei.c:1601
filename_create+0x25f/0x4f0 fs/namei.c:3807
do_symlinkat+0xe4/0x600 fs/namei.c:4419
__do_sys_symlinkat fs/namei.c:4446 [inline]
__se_sys_symlinkat fs/namei.c:4443 [inline]
__x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4443
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+0x63/0xcd
RIP: 0033:0x7fb4f468b639
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb4f399c168 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007fb4f47ac2c0 RCX: 00007fb4f468b639
RDX: 0000000020000980 RSI: 0000000000000007 RDI: 00000000200001c0
RBP: 00007fb4f46e67e1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc2217a09f R14: 00007fb4f399c300 R15: 0000000000022000
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 19af4a4ed414 Merge branch 'for-next/core', remote-tracking..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=15da0ec9680000
kernel config: https://syzkaller.appspot.com/x/.config?x=80eedef55cd21fa4
dashboard link: https://syzkaller.appspot.com/bug?extid=95cb07e3840546a4827b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11957c65680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1304e6ba680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/702d996331e0/disk-19af4a4e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2a48ce0aeb32/vmlinux-19af4a4e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/332eb4a803d2/Image-19af4a4e.gz.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/a4536cf3a09f/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/88a36e03ffba/mount_3.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+95cb07...@syzkaller.appspotmail.com

REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.

======================================================
WARNING: possible circular locking dependency detected

6.6.0-rc4-syzkaller-g19af4a4ed414 #0 Not tainted
------------------------------------------------------
syz-executor324/6098 is trying to acquire lock:
ffff0000dd376640 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:837 [inline]
ffff0000dd376640 (&type->i_mutex_dir_key#6/1){+.+.}-{3:3}, at: filename_create+0x204/0x468 fs/namei.c:3889

but task is already holding lock:

ffff0000d494e410 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:403

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#8){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1571 [inline]
sb_start_write+0x60/0x2ec include/linux/fs.h:1646
mnt_want_write_file+0x64/0x1e8 fs/namespace.c:447
reiserfs_ioctl+0x188/0x42c fs/reiserfs/ioctl.c:103
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl fs/ioctl.c:857 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595

-> #1 (&sbi->lock){+.+.}-{3:3}:
__mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:799
reiserfs_write_lock+0x7c/0xe8 fs/reiserfs/lock.c:27
reiserfs_lookup+0x128/0x45c fs/reiserfs/namei.c:364
lookup_one_qstr_excl+0x108/0x230 fs/namei.c:1608
filename_create+0x230/0x468 fs/namei.c:3890
do_mkdirat+0xac/0x610 fs/namei.c:4135
__do_sys_mkdirat fs/namei.c:4158 [inline]
__se_sys_mkdirat fs/namei.c:4156 [inline]
__arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4156
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595

-> #0 (
&type->i_mutex_dir_key#6/1){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x3370/0x75e8 kernel/locking/lockdep.c:5136
lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
down_write_nested+0x58/0xcc kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:837 [inline]
filename_create+0x204/0x468 fs/namei.c:3889
do_mkdirat+0xac/0x610 fs/namei.c:4135
__do_sys_mkdirat fs/namei.c:4158 [inline]
__se_sys_mkdirat fs/namei.c:4156 [inline]
__arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4156
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595

other info that might help us debug this:

Chain exists of:

&type->i_mutex_dir_key#6/1 --> &sbi->lock --> sb_writers#8

Possible unsafe locking scenario:

CPU0 CPU1
---- ----

rlock(sb_writers#8);
lock(&sbi->lock);
lock(sb_writers#8);
lock(&type->i_mutex_dir_key#6/1);

*** DEADLOCK ***

1 lock held by syz-executor324/6098:
#0: ffff0000d494e410 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:403

stack backtrace:
CPU: 1 PID: 6098 Comm: syz-executor324 Not tainted 6.6.0-rc4-syzkaller-g19af4a4ed414 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Call trace:
dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:233
show_stack+0x2c/0x44 arch/arm64/kernel/stacktrace.c:240
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd0/0x124 lib/dump_stack.c:106
dump_stack+0x1c/0x28 lib/dump_stack.c:113
print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2060
check_noncircular+0x310/0x404 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x3370/0x75e8 kernel/locking/lockdep.c:5136
lock_acquire+0x23c/0x71c kernel/locking/lockdep.c:5753
down_write_nested+0x58/0xcc kernel/locking/rwsem.c:1689
inode_lock_nested include/linux/fs.h:837 [inline]
filename_create+0x204/0x468 fs/namei.c:3889
do_mkdirat+0xac/0x610 fs/namei.c:4135
__do_sys_mkdirat fs/namei.c:4158 [inline]
__se_sys_mkdirat fs/namei.c:4156 [inline]
__arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4156
__invoke_syscall arch/arm64/kernel/syscall.c:37 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155
el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[Hillf Danton]

On Tue, 10 Oct 2023 12:38:42 -0700

> HEAD commit: 19af4a4ed414 Merge branch 'for-next/core', remote-tracking..
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1304e6ba680000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

--- x/fs/reiserfs/ioctl.c
+++ y/fs/reiserfs/ioctl.c
@@ -78,6 +78,9 @@ long reiserfs_ioctl(struct file *filp, u
struct inode *inode = file_inode(filp);
int err = 0;

+ err = mnt_want_write_file(filp);
+ if (err)
+ return err;
reiserfs_write_lock(inode->i_sb);

switch (cmd) {
@@ -100,23 +103,19 @@ long reiserfs_ioctl(struct file *filp, u
err = -EPERM;
break;
}
- err = mnt_want_write_file(filp);
- if (err)
- break;
if (get_user(inode->i_generation, (int __user *)arg)) {
err = -EFAULT;
- goto setversion_out;
+ break;
}
inode_set_ctime_current(inode);
mark_inode_dirty(inode);
-setversion_out:
- mnt_drop_write_file(filp);
break;
default:
err = -ENOTTY;
}

reiserfs_write_unlock(inode->i_sb);
+ mnt_drop_write_file(filp);

return err;
}
--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+95cb07...@syzkaller.appspotmail.com

Tested on:

commit: 1c8b86a3 Merge tag 'xsa441-6.6-tag' of git://git.kerne..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=10539c65680000
kernel config: https://syzkaller.appspot.com/x/.config?x=1b8c825e0d5f3f72

dashboard link: https://syzkaller.appspot.com/bug?extid=95cb07e3840546a4827b
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

patch: https://syzkaller.appspot.com/x/patch.diff?x=170ed9b5680000

Note: testing is done by a robot and is best-effort only.

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.