Re: [syzbot] [ntfs3?] possible deadlock in ntfs_fiemap

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in ntfs_fiemap

loop0: detected capacity change from 0 to 4096
ntfs3: loop0: Different NTFS sector size (4096) and media sector size (512).
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc1-syzkaller-00035-gd57431c6f511 #0 Not tainted
------------------------------------------------------
syz-executor.0/5466 is trying to acquire lock:
ffff88801bb51e18 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0xaa/0x120 mm/memory.c:6233

but task is already holding lock:
ffff88807905d220 (&ni->ni_lock/4){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1107 [inline]
ffff88807905d220 (&ni->ni_lock/4){+.+.}-{3:3}, at: ntfs_fiemap+0xff/0x180 fs/ntfs3/file.c:1211

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->ni_lock/4){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
       ni_lock fs/ntfs3/ntfs_fs.h:1107 [inline]
       attr_data_get_block+0x463/0x2ff0 fs/ntfs3/attrib.c:917
       ntfs_file_mmap+0x50e/0x860 fs/ntfs3/file.c:294
       call_mmap include/linux/fs.h:2107 [inline]
       mmap_region+0xe8f/0x2090 mm/mmap.c:2886
       do_mmap+0x8ad/0xfa0 mm/mmap.c:1397
       vm_mmap_pgoff+0x1dd/0x3d0 mm/util.c:573
       ksys_mmap_pgoff+0x4f1/0x720 mm/mmap.c:1443
       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

-> #0 (&mm->mmap_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       __might_fault+0xc6/0x120 mm/memory.c:6233
       _copy_to_user+0x2a/0xb0 lib/usercopy.c:41
       copy_to_user include/linux/uaccess.h:191 [inline]
       fiemap_fill_next_extent+0x235/0x410 fs/ioctl.c:145
       ni_fiemap+0x4f5/0x1910 fs/ntfs3/frecord.c:1993
       ntfs_fiemap+0x132/0x180 fs/ntfs3/file.c:1213
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x1c07/0x2e50 fs/ioctl.c:841
       __do_sys_ioctl fs/ioctl.c:905 [inline]
       __se_sys_ioctl+0x81/0x170 fs/ioctl.c:893
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ni->ni_lock/4);
                               lock(&mm->mmap_lock);
                               lock(&ni->ni_lock/4);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

1 lock held by syz-executor.0/5466:
 #0: ffff88807905d220 (&ni->ni_lock/4){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1107 [inline]
 #0: ffff88807905d220 (&ni->ni_lock/4){+.+.}-{3:3}, at: ntfs_fiemap+0xff/0x180 fs/ntfs3/file.c:1211

stack backtrace:
CPU: 1 PID: 5466 Comm: syz-executor.0 Not tainted 6.10.0-rc1-syzkaller-00035-gd57431c6f511 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 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+0x18e0/0x5900 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 __might_fault+0xc6/0x120 mm/memory.c:6233
 _copy_to_user+0x2a/0xb0 lib/usercopy.c:41
 copy_to_user include/linux/uaccess.h:191 [inline]
 fiemap_fill_next_extent+0x235/0x410 fs/ioctl.c:145
 ni_fiemap+0x4f5/0x1910 fs/ntfs3/frecord.c:1993
 ntfs_fiemap+0x132/0x180 fs/ntfs3/file.c:1213
 ioctl_fiemap fs/ioctl.c:220 [inline]
 do_vfs_ioctl+0x1c07/0x2e50 fs/ioctl.c:841
 __do_sys_ioctl fs/ioctl.c:905 [inline]
 __se_sys_ioctl+0x81/0x170 fs/ioctl.c:893
 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: 0033:0x7f26c7a7dea9
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:00007f26c889e0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f26c7babf80 RCX: 00007f26c7a7dea9
RDX: 0000000020000280 RSI: 00000000c020660b RDI: 0000000000000005
RBP: 00007f26c7aca4a4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f26c7babf80 R15: 00007ffd4e86fce8
 </TASK>


Tested on:

commit:         d57431c6 fs/ntfs3: Do copy_to_user out of run_lock
git tree:       https://github.com/Paragon-Software-Group/linux-ntfs3.git
console output: https://syzkaller.appspot.com/x/log.txt?x=11deb321980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b9016f104992d69c
dashboard link: https://syzkaller.appspot.com/bug?extid=96cee7d33ca3f87eee86
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.