syzbot

overlayfs: failed to resolve './file0': -2
======================================================
WARNING: possible circular locking dependency detected
4.19.211-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor256/22187 is trying to acquire lock:
000000009314fca8 (&pipe->mutex/1){+.+.}, at: pipe_lock_nested fs/pipe.c:77 [inline]
000000009314fca8 (&pipe->mutex/1){+.+.}, at: pipe_lock+0x63/0x80 fs/pipe.c:85

but task is already holding lock:
00000000fdb1f0b3 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2779 [inline]
00000000fdb1f0b3 (sb_writers#3){.+.+}, at: do_splice fs/splice.c:1153 [inline]
00000000fdb1f0b3 (sb_writers#3){.+.+}, at: __do_sys_splice fs/splice.c:1428 [inline]
00000000fdb1f0b3 (sb_writers#3){.+.+}, at: __se_sys_splice+0x11de/0x16d0 fs/splice.c:1408

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_writers#3){.+.+}:
       sb_start_write include/linux/fs.h:1579 [inline]
       mnt_want_write+0x3a/0xb0 fs/namespace.c:360
       ovl_setattr+0xdd/0x920 fs/overlayfs/inode.c:30
       notify_change+0x70b/0xfc0 fs/attr.c:334
       do_truncate+0x134/0x1f0 fs/open.c:63
       handle_truncate fs/namei.c:3009 [inline]
       do_last fs/namei.c:3427 [inline]
       path_openat+0x2308/0x2df0 fs/namei.c:3537
       do_filp_open+0x18c/0x3f0 fs/namei.c:3567
       do_sys_open+0x3b3/0x520 fs/open.c:1085
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #1 (&ovl_i_mutex_key[depth]){+.+.}:
       inode_lock include/linux/fs.h:748 [inline]
       ovl_write_iter+0x148/0xb40 fs/overlayfs/file.c:270
       call_write_iter include/linux/fs.h:1821 [inline]
       new_sync_write fs/read_write.c:474 [inline]
       __vfs_write+0x51b/0x770 fs/read_write.c:487
       __kernel_write+0x109/0x370 fs/read_write.c:506
       write_pipe_buf+0x153/0x1f0 fs/splice.c:798
       splice_from_pipe_feed fs/splice.c:503 [inline]
       __splice_from_pipe+0x389/0x800 fs/splice.c:627
       splice_from_pipe fs/splice.c:662 [inline]
       default_file_splice_write+0xd8/0x180 fs/splice.c:810
       do_splice_from fs/splice.c:852 [inline]
       do_splice fs/splice.c:1154 [inline]
       __do_sys_splice fs/splice.c:1428 [inline]
       __se_sys_splice+0xfe7/0x16d0 fs/splice.c:1408
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> #0 (&pipe->mutex/1){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:937 [inline]
       __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078
       pipe_lock_nested fs/pipe.c:77 [inline]
       pipe_lock+0x63/0x80 fs/pipe.c:85
       iter_file_splice_write+0x183/0xbb0 fs/splice.c:700
       do_splice_from fs/splice.c:852 [inline]
       do_splice fs/splice.c:1154 [inline]
       __do_sys_splice fs/splice.c:1428 [inline]
       __se_sys_splice+0xfe7/0x16d0 fs/splice.c:1408
       do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  &pipe->mutex/1 --> &ovl_i_mutex_key[depth] --> sb_writers#3

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(sb_writers#3);
                               lock(&ovl_i_mutex_key[depth]);
                               lock(sb_writers#3);
  lock(&pipe->mutex/1);

 *** DEADLOCK ***

1 lock held by syz-executor256/22187:
 #0: 00000000fdb1f0b3 (sb_writers#3){.+.+}, at: file_start_write include/linux/fs.h:2779 [inline]
 #0: 00000000fdb1f0b3 (sb_writers#3){.+.+}, at: do_splice fs/splice.c:1153 [inline]
 #0: 00000000fdb1f0b3 (sb_writers#3){.+.+}, at: __do_sys_splice fs/splice.c:1428 [inline]
 #0: 00000000fdb1f0b3 (sb_writers#3){.+.+}, at: __se_sys_splice+0x11de/0x16d0 fs/splice.c:1408

stack backtrace:
CPU: 0 PID: 22187 Comm: syz-executor256 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1222
 check_prev_add kernel/locking/lockdep.c:1866 [inline]
 check_prevs_add kernel/locking/lockdep.c:1979 [inline]
 validate_chain kernel/locking/lockdep.c:2420 [inline]
 __lock_acquire+0x30c9/0x3ff0 kernel/locking/lockdep.c:3416
 lock_acquire+0x170/0x3c0 kernel/locking/lockdep.c:3908
 __mutex_lock_common kernel/locking/mutex.c:937 [inline]
 __mutex_lock+0xd7/0x1190 kernel/locking/mutex.c:1078
 pipe_lock_nested fs/pipe.c:77 [inline]
 pipe_lock+0x63/0x80 fs/pipe.c:85
 iter_file_splice_write+0x183/0xbb0 fs/splice.c:700
 do_splice_from fs/splice.c:852 [inline]
 do_splice fs/splice.c:1154 [inline]
 __do_sys_splice fs/splice.c:1428 [inline]
 __se_sys_splice+0xfe7/0x16d0 fs/splice.c:1408
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f7796c20649
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7796bc92e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f7796ca24c0 RCX: 00007f7796c20649
RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f7796c6f140 R08: 000000000000fdef R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0030656c69662f2e
R13: 3d7269647265776f R14: 0079616c7265766f R15: 00007f7796ca24c8