Message-ID: <20240213114151.982-1-hdanton@sina.com>
Date: Tue, 13 Feb 2024 19:41:50 +0800
From: Hillf Danton <hdanton@...a.com>
To: syzbot <syzbot+c2ada45c23d98d646118@...kaller.appspotmail.com>
Cc: almaz.alexandrovich@...agon-software.com,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	ntfs3@...ts.linux.dev,
	Boqun Feng <boqun.feng@...il.com>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [ntfs3?] possible deadlock in ntfs_set_state (2)

On Mon, 12 Feb 2024 23:12:22 -0800
> HEAD commit:    716f4aaa7b48 Merge tag 'vfs-6.8-rc5.fixes' of git://git.ke..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=100fd062180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1d7c92dd8d5c7a1e
> dashboard link: https://syzkaller.appspot.com/bug?extid=c2ada45c23d98d646118
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11fcbd48180000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17f6e642180000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/ca4bf59e5a18/disk-716f4aaa.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/3d7ade517e63/vmlinux-716f4aaa.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/e13f7054c0c1/bzImage-716f4aaa.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/00ba9c2f3dd0/mount_0.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c2ada45c23d98d646118@...kaller.appspotmail.com
> 
> loop0: detected capacity change from 0 to 4096
> ntfs3: loop0: Different NTFS sector size (4096) and media sector size (512).
> ntfs3: loop0: ino=5, "/" ntfs_iget5
> ============================================
> WARNING: possible recursive locking detected
> 6.8.0-rc4-syzkaller-00003-g716f4aaa7b48 #0 Not tainted
> --------------------------------------------
> syz-executor354/5071 is trying to acquire lock:
> ffff888070ee0100 (&ni->ni_lock#3){+.+.}-{3:3}, at: ntfs_set_state+0x1ff/0x6c0 fs/ntfs3/fsntfs.c:947
> 
> but task is already holding lock:
> ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_trylock fs/ntfs3/ntfs_fs.h:1141 [inline]
> ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_write_inode+0x1bc/0x1010 fs/ntfs3/frecord.c:3265
> 
This report looks false positive but raises the question -- what made lockedp
pull the wrong trigger? Because of the correct lock_class_key in mutex_init()
instead of &ni->ni_lock?

> other info that might help us debug this:
>  Possible unsafe locking scenario:
> 
>        CPU0
>        ----
>   lock(&ni->ni_lock#3);
>   lock(&ni->ni_lock#3);
> 
>  *** DEADLOCK ***
> 
>  May be due to missing lock nesting notation
> 
> 3 locks held by syz-executor354/5071:
>  #0: ffff88802223a420 (sb_writers#9){.+.+}-{0:0}, at: do_sys_ftruncate+0x25c/0x390 fs/open.c:191
>  #1: ffff888070de3ea0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline]
>  #1: ffff888070de3ea0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: do_truncate+0x20c/0x310 fs/open.c:64
>  #2: ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_trylock fs/ntfs3/ntfs_fs.h:1141 [inline]
>  #2: ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_write_inode+0x1bc/0x1010 fs/ntfs3/frecord.c:3265
> 
> stack backtrace:
> CPU: 0 PID: 5071 Comm: syz-executor354 Not tainted 6.8.0-rc4-syzkaller-00003-g716f4aaa7b48 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
>  check_deadlock kernel/locking/lockdep.c:3062 [inline]
>  validate_chain+0x15c0/0x58e0 kernel/locking/lockdep.c:3856
>  __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137
>  lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754
>  __mutex_lock_common kernel/locking/mutex.c:608 [inline]
>  __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
>  ntfs_set_state+0x1ff/0x6c0 fs/ntfs3/fsntfs.c:947
>  ntfs_iget5+0x3f0/0x3b70 fs/ntfs3/inode.c:535
>  ni_update_parent+0x943/0xdd0 fs/ntfs3/frecord.c:3218
>  ni_write_inode+0xde9/0x1010 fs/ntfs3/frecord.c:3324
>  ntfs_truncate fs/ntfs3/file.c:410 [inline]
>  ntfs3_setattr+0x950/0xb40 fs/ntfs3/file.c:703
>  notify_change+0xb9f/0xe70 fs/attr.c:499
>  do_truncate+0x220/0x310 fs/open.c:66
>  do_sys_ftruncate+0x2f7/0x390 fs/open.c:194
>  do_syscall_64+0xfb/0x240
>  entry_SYSCALL_64_after_hwframe+0x6f/0x77
> RIP: 0033:0x7fd0ca446639
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 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:00007fff0baab678 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
> RAX: ffffffffffffffda RBX: 00007fff0baab848 RCX: 00007fd0ca446639
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
> RBP: 00007fd0ca4d8610 R08: 0000000000000000 R09: 00007fff0baab848
> R10: 000000000001f20a R11: 0000000000000246 R12: 0000000000000001
> R13: 00007fff0baab838 R14: 0000000000000001 R15: 0000000000000001
>  </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 syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
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> 
> If the report is already addressed, let syzbot know by replying with:
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> 
> If you want syzbot to run the reproducer, reply with:
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> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
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> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup
> 

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