Message-ID: <67290b04.050a0220.2edce.14f8.GAE@google.com>
Date: Mon, 04 Nov 2024 09:57:24 -0800
From: syzbot <syzbot+d472c32c5dd4cd2fb5c5@...kaller.appspotmail.com>
To: jack@...e.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [udf?] possible deadlock in udf_free_blocks

Hello,

syzbot found the following issue on:

HEAD commit:    0fc810ae3ae1 x86/uaccess: Avoid barrier_nospec() in 64-bit..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1106e55f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4aec7739e14231a7
dashboard link: https://syzkaller.appspot.com/bug?extid=d472c32c5dd4cd2fb5c5
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-0fc810ae.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/35cb2385689e/vmlinux-0fc810ae.xz
kernel image: https://storage.googleapis.com/syzbot-assets/32b7d90faa74/bzImage-0fc810ae.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d472c32c5dd4cd2fb5c5@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 2048
=======================================================
WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
UDF-fs: error (device loop0): udf_read_tagged: tag checksum failed, block 99: 0x27 != 0x4d
UDF-fs: error (device loop0): udf_read_tagged: tag checksum failed, block 160: 0xd2 != 0xd4
UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2022/11/22 14:59 (1000)
============================================
WARNING: possible recursive locking detected
6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0 Not tainted
--------------------------------------------
syz.0.0/5328 is trying to acquire lock:
ffff8880432e6128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_free_blocks fs/udf/balloc.c:375 [inline]
ffff8880432e6128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_free_blocks+0x9ff/0x2270 fs/udf/balloc.c:677

but task is already holding lock:
ffff8880432e6128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
ffff8880432e6128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_prealloc_blocks+0x820/0x13d0 fs/udf/balloc.c:701

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&sbi->s_alloc_mutex);
  lock(&sbi->s_alloc_mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by syz.0.0/5328:
 #0: ffff8880438b6420 (sb_writers#11){.+.+}-{0:0}, at: direct_splice_actor+0x49/0x220 fs/splice.c:1163
 #1: ffff888043f24f60 (&sb->s_type->i_mutex_key#19){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
 #1: ffff888043f24f60 (&sb->s_type->i_mutex_key#19){+.+.}-{3:3}, at: udf_file_write_iter+0x6f/0x660 fs/udf/file.c:95
 #2: ffff888043f24d90 (&ei->i_data_sem#2){++++}-{3:3}, at: udf_map_block+0x3b7/0x5340 fs/udf/inode.c:439
 #3: ffff8880432e6128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_table_prealloc_blocks fs/udf/balloc.c:516 [inline]
 #3: ffff8880432e6128 (&sbi->s_alloc_mutex){+.+.}-{3:3}, at: udf_prealloc_blocks+0x820/0x13d0 fs/udf/balloc.c:701

stack backtrace:
CPU: 0 UID: 0 PID: 5328 Comm: syz.0.0 Not tainted 6.12.0-rc5-syzkaller-00063-g0fc810ae3ae1 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_deadlock_bug+0x483/0x620 kernel/locking/lockdep.c:3037
 check_deadlock kernel/locking/lockdep.c:3089 [inline]
 validate_chain+0x15e2/0x5920 kernel/locking/lockdep.c:3891
 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
 udf_table_free_blocks fs/udf/balloc.c:375 [inline]
 udf_free_blocks+0x9ff/0x2270 fs/udf/balloc.c:677
 udf_delete_aext+0x70a/0xed0 fs/udf/inode.c:2372
 udf_table_prealloc_blocks fs/udf/balloc.c:543 [inline]
 udf_prealloc_blocks+0xf2b/0x13d0 fs/udf/balloc.c:701
 udf_prealloc_extents fs/udf/inode.c:1052 [inline]
 inode_getblk fs/udf/inode.c:910 [inline]
 udf_map_block+0x284a/0x5340 fs/udf/inode.c:447
 __udf_get_block+0x126/0x410 fs/udf/inode.c:461
 __block_write_begin_int+0x50c/0x1a70 fs/buffer.c:2121
 block_write_begin+0x8f/0x120 fs/buffer.c:2231
 udf_write_begin+0x104/0x350 fs/udf/inode.c:256
 generic_perform_write+0x344/0x6d0 mm/filemap.c:4054
 __generic_file_write_iter+0x1b5/0x230 mm/filemap.c:4152
 udf_file_write_iter+0x2fc/0x660 fs/udf/file.c:111
 iter_file_splice_write+0xbfa/0x1510 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x11b/0x220 fs/splice.c:1164
 splice_direct_to_actor+0x586/0xc80 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0x289/0x3e0 fs/splice.c:1233
 do_sendfile+0x561/0xe10 fs/read_write.c:1388
 __do_sys_sendfile64 fs/read_write.c:1455 [inline]
 __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1441
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe35557e719
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe35644a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fe355735f80 RCX: 00007fe35557e719
RDX: 0000000000000000 RSI: 000000000000000a RDI: 000000000000000a
RBP: 00007fe3555f132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000800000009 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe355735f80 R15: 00007ffcceb987c8
 </TASK>


---
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