Message-ID: <67865c9e.050a0220.216c54.0077.GAE@google.com>
Date: Tue, 14 Jan 2025 04:46:22 -0800
From: syzbot <syzbot+d27edf9f96ae85939222@...kaller.appspotmail.com>
To: almaz.alexandrovich@...agon-software.com, linux-kernel@...r.kernel.org, 
	ntfs3@...ts.linux.dev, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [ntfs3?] possible deadlock in ntfs_look_for_free_space

syzbot has found a reproducer for the following issue on:

HEAD commit:    c45323b7560e Merge tag 'mm-hotfixes-stable-2025-01-13-00-0..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11732a18580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=aadf89e2f6db86cc
dashboard link: https://syzkaller.appspot.com/bug?extid=d27edf9f96ae85939222
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=16825bc4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/32d07cc6940f/disk-c45323b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8e06bc34aa34/vmlinux-c45323b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0b63902920e8/bzImage-c45323b7.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/66d38d2d76ad/mount_1.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/386eda454648/mount_6.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d27edf9f96ae85939222@...kaller.appspotmail.com

loop3: detected capacity change from 0 to 4096
ntfs3(loop3): Different NTFS sector size (1024) and media sector size (512).
======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc7-syzkaller-00019-gc45323b7560e #0 Not tainted
------------------------------------------------------
syz.3.19/6137 is trying to acquire lock:
ffff8880325ba270 (&wnd->rw_lock){++++}-{4:4}, at: ntfs_look_for_free_space+0x100/0x690 fs/ntfs3/fsntfs.c:362

but task is already holding lock:
ffff88805a99bc70 (&ni->file.run_lock#2){++++}-{4:4}, at: ntfs_extend_mft+0x160/0x4b0 fs/ntfs3/fsntfs.c:511

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->file.run_lock#2){++++}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       down_read+0xb1/0xa40 kernel/locking/rwsem.c:1524
       run_unpack_ex+0x55e/0x9e0 fs/ntfs3/run.c:1119
       ntfs_read_mft fs/ntfs3/inode.c:401 [inline]
       ntfs_iget5+0x1f9a/0x37b0 fs/ntfs3/inode.c:537
       ntfs_dir_emit fs/ntfs3/dir.c:335 [inline]
       ntfs_read_hdr+0x700/0xb80 fs/ntfs3/dir.c:383
       ntfs_readdir+0x91f/0xf00 fs/ntfs3/dir.c:494
       iterate_dir+0x573/0x800 fs/readdir.c:108
       __do_sys_getdents64 fs/readdir.c:403 [inline]
       __se_sys_getdents64+0x1e2/0x4b0 fs/readdir.c:389
       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 (&wnd->rw_lock){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
       down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693
       ntfs_look_for_free_space+0x100/0x690 fs/ntfs3/fsntfs.c:362
       attr_allocate_clusters+0x1d6/0x990 fs/ntfs3/attrib.c:159
       attr_set_size+0x2053/0x4300 fs/ntfs3/attrib.c:574
       ntfs_extend_mft+0x188/0x4b0 fs/ntfs3/fsntfs.c:512
       ntfs_look_free_mft+0x77c/0x10c0 fs/ntfs3/fsntfs.c:709
       ntfs_create_inode+0x581/0x3760 fs/ntfs3/inode.c:1305
       ntfs_create+0x3d/0x50 fs/ntfs3/namei.c:110
       lookup_open fs/namei.c:3649 [inline]
       open_last_lookups fs/namei.c:3748 [inline]
       path_openat+0x1c05/0x3590 fs/namei.c:3984
       do_filp_open+0x27f/0x4e0 fs/namei.c:4014
       do_sys_openat2+0x13e/0x1d0 fs/open.c:1402
       do_sys_open fs/open.c:1417 [inline]
       __do_sys_creat fs/open.c:1495 [inline]
       __se_sys_creat fs/open.c:1489 [inline]
       __x64_sys_creat+0x123/0x170 fs/open.c:1489
       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->file.run_lock#2);
                               lock(&wnd->rw_lock);
                               lock(&ni->file.run_lock#2);
  lock(&wnd->rw_lock);

 *** DEADLOCK ***

5 locks held by syz.3.19/6137:
 #0: ffff8880325bc420 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:516
 #1: ffff88805a845bb8 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
 #1: ffff88805a845bb8 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: open_last_lookups fs/namei.c:3745 [inline]
 #1: ffff88805a845bb8 (&type->i_mutex_dir_key#10){++++}-{4:4}, at: path_openat+0x89a/0x3590 fs/namei.c:3984
 #2: ffff88805a845920 (&ni->ni_lock/6){+.+.}-{4:4}, at: ni_lock_dir fs/ntfs3/ntfs_fs.h:1115 [inline]
 #2: ffff88805a845920 (&ni->ni_lock/6){+.+.}-{4:4}, at: ntfs_create_inode+0x215/0x3760 fs/ntfs3/inode.c:1219
 #3: ffff8880325ba128 (&wnd->rw_lock/1){+.+.}-{4:4}, at: ntfs_look_free_mft+0x1e5/0x10c0 fs/ntfs3/fsntfs.c:571
 #4: ffff88805a99bc70 (&ni->file.run_lock#2){++++}-{4:4}, at: ntfs_extend_mft+0x160/0x4b0 fs/ntfs3/fsntfs.c:511

stack backtrace:
CPU: 0 UID: 0 PID: 6137 Comm: syz.3.19 Not tainted 6.13.0-rc7-syzkaller-00019-gc45323b7560e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693
 ntfs_look_for_free_space+0x100/0x690 fs/ntfs3/fsntfs.c:362
 attr_allocate_clusters+0x1d6/0x990 fs/ntfs3/attrib.c:159
 attr_set_size+0x2053/0x4300 fs/ntfs3/attrib.c:574
 ntfs_extend_mft+0x188/0x4b0 fs/ntfs3/fsntfs.c:512
 ntfs_look_free_mft+0x77c/0x10c0 fs/ntfs3/fsntfs.c:709
 ntfs_create_inode+0x581/0x3760 fs/ntfs3/inode.c:1305
 ntfs_create+0x3d/0x50 fs/ntfs3/namei.c:110
 lookup_open fs/namei.c:3649 [inline]
 open_last_lookups fs/namei.c:3748 [inline]
 path_openat+0x1c05/0x3590 fs/namei.c:3984
 do_filp_open+0x27f/0x4e0 fs/namei.c:4014
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1402
 do_sys_open fs/open.c:1417 [inline]
 __do_sys_creat fs/open.c:1495 [inline]
 __se_sys_creat fs/open.c:1489 [inline]
 __x64_sys_creat+0x123/0x170 fs/open.c:1489
 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: 0033:0x7f07c8f85d29
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:00007f07c9de6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007f07c9175fa0 RCX: 00007f07c8f85d29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000240
RBP: 00007f07c9001b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f07c9175fa0 R15: 00007fff8eee1d18
 </TASK>
ntfs3(loop3): ino=0, attr_set_size


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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