Message-ID: <000000000000ca2df5060676b6d8@google.com>
Date:   Thu, 28 Sep 2023 20:06:42 -0700
From:   syzbot <syzbot+e8628856801e9809216f@...kaller.appspotmail.com>
To:     amir73il@...il.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-unionfs@...r.kernel.org,
        miklos@...redi.hu, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [overlayfs?] possible deadlock in ovl_copy_up_start (2)

Hello,

syzbot found the following issue on:

HEAD commit:    940fcc189c51 Add linux-next specific files for 20230921
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12dea70e680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1f140ae6e669ac24
dashboard link: https://syzkaller.appspot.com/bug?extid=e8628856801e9809216f
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b8921b235c24/disk-940fcc18.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c80a9f6bcdd4/vmlinux-940fcc18.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ed10a4df6950/bzImage-940fcc18.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e8628856801e9809216f@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.6.0-rc2-next-20230921-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.3/15498 is trying to acquire lock:
ffff88808e717968 (&ovl_i_lock_key[depth]#2){+.+.}-{3:3}, at: ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:630 [inline]
ffff88808e717968 (&ovl_i_lock_key[depth]#2){+.+.}-{3:3}, at: ovl_copy_up_start+0x4d/0x290 fs/overlayfs/util.c:692

but task is already holding lock:
ffff88801d8b13e0 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x893/0x1cc0 security/integrity/ima/ima_main.c:266

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&iint->mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       process_measurement+0x893/0x1cc0 security/integrity/ima/ima_main.c:266
       ima_file_check+0xc2/0x110 security/integrity/ima/ima_main.c:543
       do_open fs/namei.c:3622 [inline]
       path_openat+0x17a1/0x29c0 fs/namei.c:3777
       do_filp_open+0x1de/0x430 fs/namei.c:3804
       do_sys_openat2+0x176/0x1e0 fs/open.c:1422
       do_sys_open fs/open.c:1437 [inline]
       __do_sys_open fs/open.c:1445 [inline]
       __se_sys_open fs/open.c:1441 [inline]
       __x64_sys_open+0x154/0x1e0 fs/open.c:1441
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (sb_writers#4){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1572 [inline]
       sb_start_write include/linux/fs.h:1647 [inline]
       ovl_start_write+0xfe/0x2d0 fs/overlayfs/util.c:31
       ovl_copy_up_tmpfile fs/overlayfs/copy_up.c:830 [inline]
       ovl_do_copy_up fs/overlayfs/copy_up.c:945 [inline]
       ovl_copy_up_one+0x16a5/0x3250 fs/overlayfs/copy_up.c:1137
       ovl_copy_up_flags+0x189/0x200 fs/overlayfs/copy_up.c:1192
       ovl_xattr_set+0x387/0x4e0 fs/overlayfs/xattrs.c:56
       __vfs_setxattr+0x173/0x1d0 fs/xattr.c:201
       __vfs_setxattr_noperm+0x127/0x5e0 fs/xattr.c:235
       __vfs_setxattr_locked+0x17e/0x250 fs/xattr.c:296
       vfs_setxattr+0x146/0x350 fs/xattr.c:322
       do_setxattr+0x142/0x170 fs/xattr.c:630
       setxattr+0x159/0x170 fs/xattr.c:653
       path_setxattr+0x1a3/0x1d0 fs/xattr.c:672
       __do_sys_setxattr fs/xattr.c:688 [inline]
       __se_sys_setxattr fs/xattr.c:684 [inline]
       __x64_sys_setxattr+0xc4/0x160 fs/xattr.c:684
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&ovl_i_lock_key[depth]#2){+.+.}-{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+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
       lock_acquire kernel/locking/lockdep.c:5753 [inline]
       lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
       ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:630 [inline]
       ovl_copy_up_start+0x4d/0x290 fs/overlayfs/util.c:692
       ovl_copy_up_one+0x598/0x3250 fs/overlayfs/copy_up.c:1130
       ovl_copy_up_flags+0x189/0x200 fs/overlayfs/copy_up.c:1192
       ovl_maybe_copy_up+0x124/0x160 fs/overlayfs/copy_up.c:1222
       ovl_open+0x16f/0x330 fs/overlayfs/file.c:166
       do_dentry_open+0x88b/0x1730 fs/open.c:929
       vfs_open fs/open.c:1063 [inline]
       dentry_open+0x13f/0x1d0 fs/open.c:1079
       ima_calc_file_hash+0x2c4/0x4a0 security/integrity/ima/ima_crypto.c:558
       ima_collect_measurement+0x5e2/0x6f0 security/integrity/ima/ima_api.c:289
       process_measurement+0xc87/0x1cc0 security/integrity/ima/ima_main.c:345
       ima_file_check+0xc2/0x110 security/integrity/ima/ima_main.c:543
       do_open fs/namei.c:3622 [inline]
       path_openat+0x17a1/0x29c0 fs/namei.c:3777
       do_filp_open+0x1de/0x430 fs/namei.c:3804
       do_sys_openat2+0x176/0x1e0 fs/open.c:1422
       do_sys_open fs/open.c:1437 [inline]
       __do_sys_openat fs/open.c:1453 [inline]
       __se_sys_openat fs/open.c:1448 [inline]
       __x64_sys_openat+0x175/0x210 fs/open.c:1448
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  &ovl_i_lock_key[depth]#2 --> sb_writers#4 --> &iint->mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&iint->mutex);
                               lock(sb_writers#4);
                               lock(&iint->mutex);
  lock(&ovl_i_lock_key[depth]#2);

 *** DEADLOCK ***

1 lock held by syz-executor.3/15498:
 #0: ffff88801d8b13e0 (&iint->mutex){+.+.}-{3:3}, at: process_measurement+0x893/0x1cc0 security/integrity/ima/ima_main.c:266

stack backtrace:
CPU: 0 PID: 15498 Comm: syz-executor.3 Not tainted 6.6.0-rc2-next-20230921-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
 check_noncircular+0x311/0x3f0 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+0x2e3d/0x5de0 kernel/locking/lockdep.c:5136
 lock_acquire kernel/locking/lockdep.c:5753 [inline]
 lock_acquire+0x1ae/0x510 kernel/locking/lockdep.c:5718
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x181/0x1340 kernel/locking/mutex.c:747
 ovl_inode_lock_interruptible fs/overlayfs/overlayfs.h:630 [inline]
 ovl_copy_up_start+0x4d/0x290 fs/overlayfs/util.c:692
 ovl_copy_up_one+0x598/0x3250 fs/overlayfs/copy_up.c:1130
 ovl_copy_up_flags+0x189/0x200 fs/overlayfs/copy_up.c:1192
 ovl_maybe_copy_up+0x124/0x160 fs/overlayfs/copy_up.c:1222
 ovl_open+0x16f/0x330 fs/overlayfs/file.c:166
 do_dentry_open+0x88b/0x1730 fs/open.c:929
 vfs_open fs/open.c:1063 [inline]
 dentry_open+0x13f/0x1d0 fs/open.c:1079
 ima_calc_file_hash+0x2c4/0x4a0 security/integrity/ima/ima_crypto.c:558
 ima_collect_measurement+0x5e2/0x6f0 security/integrity/ima/ima_api.c:289
 process_measurement+0xc87/0x1cc0 security/integrity/ima/ima_main.c:345
 ima_file_check+0xc2/0x110 security/integrity/ima/ima_main.c:543
 do_open fs/namei.c:3622 [inline]
 path_openat+0x17a1/0x29c0 fs/namei.c:3777
 do_filp_open+0x1de/0x430 fs/namei.c:3804
 do_sys_openat2+0x176/0x1e0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f30bf67cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f30c03990c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f30bf79c050 RCX: 00007f30bf67cae9
RDX: 0000000000008443 RSI: 0000000020004280 RDI: ffffffffffffff9c
RBP: 00007f30bf6c847a R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000000cc R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f30bf79c050 R15: 00007ffce77ebe68
 </TASK>


---
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If the bug is already fixed, let syzbot know by replying with:
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If you want to overwrite bug's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

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