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

syzbot
2024-08-02T11:23:23Z

syzbot has found a reproducer for the following issue on:

HEAD commit: c0ecd6388360 Merge tag 'pci-v6.11-fixes-1' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17478c7d980000
kernel config: https://syzkaller.appspot.com/x/.config?x=288f248fe2b6eab0
dashboard link: https://syzkaller.appspot.com/bug?extid=d7452fc408a961bcc6ec
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=142941a1980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15b302d9980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0cb5895deab9/disk-c0ecd638.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bce552aea06e/vmlinux-c0ecd638.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5489dae15424/bzImage-c0ecd638.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/56ae044ae9a1/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d7452fc408a961bcc6ec@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.11.0-rc1-syzkaller-00154-gc0ecd6388360 #0 Not tainted
------------------------------------------------------
syz-executor170/5231 is trying to acquire lock:
ffff888078ac6098 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:153

but task is already holding lock:
ffff888074715460 (&sb->s_type->i_mutex_key#14){+.+.}-{3:3}, at: inode_trylock include/linux/fs.h:819 [inline]
ffff888074715460 (&sb->s_type->i_mutex_key#14){+.+.}-{3:3}, at: ntfs_file_write_iter+0x24a/0x740 fs/ntfs3/file.c:1166

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#14){+.+.}-{3:3}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
down_write+0x99/0x220 kernel/locking/rwsem.c:1579
inode_lock include/linux/fs.h:799 [inline]
ntfs_file_mmap+0x5bf/0x850 fs/ntfs3/file.c:368
call_mmap include/linux/fs.h:2129 [inline]
mmap_region+0xe8f/0x2090 mm/mmap.c:2957
do_mmap+0x8f9/0x1010 mm/mmap.c:1468
vm_mmap_pgoff+0x1dd/0x3d0 mm/util.c:588
ksys_mmap_pgoff+0x4f1/0x720 mm/mmap.c:1514
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:3133 [inline]
check_prevs_add kernel/locking/lockdep.c:3252 [inline]
validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868
__lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
down_read_killable+0xca/0xd30 kernel/locking/rwsem.c:1549
mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:153
get_mmap_lock_carefully mm/memory.c:5879 [inline]
lock_mm_and_find_vma+0x29c/0x2f0 mm/memory.c:5930
do_user_addr_fault arch/x86/mm/fault.c:1361 [inline]
handle_page_fault arch/x86/mm/fault.c:1481 [inline]
exc_page_fault+0x1bf/0x8c0 arch/x86/mm/fault.c:1539
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
fault_in_readable+0x108/0x2b0 mm/gup.c:2236
fault_in_iov_iter_readable+0x229/0x280 lib/iov_iter.c:94
generic_perform_write+0x29f/0x840 mm/filemap.c:4009
ntfs_file_write_iter+0x663/0x740 fs/ntfs3/file.c:1193
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xa72/0xc90 fs/read_write.c:590
ksys_write+0x1a0/0x2c0 fs/read_write.c:643
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(&sb->s_type->i_mutex_key#14);
lock(&mm->mmap_lock);
lock(&sb->s_type->i_mutex_key#14);
rlock(&mm->mmap_lock);

*** DEADLOCK ***

3 locks held by syz-executor170/5231:
#0: ffff88802a594d48 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x24e/0x310 fs/file.c:1191
#1: ffff88802c5b8420 (sb_writers#9){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2876 [inline]
#1: ffff88802c5b8420 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x227/0xc90 fs/read_write.c:586
#2: ffff888074715460 (&sb->s_type->i_mutex_key#14){+.+.}-{3:3}, at: inode_trylock include/linux/fs.h:819 [inline]
#2: ffff888074715460 (&sb->s_type->i_mutex_key#14){+.+.}-{3:3}, at: ntfs_file_write_iter+0x24a/0x740 fs/ntfs3/file.c:1166

stack backtrace:
CPU: 0 UID: 0 PID: 5231 Comm: syz-executor170 Not tainted 6.11.0-rc1-syzkaller-00154-gc0ecd6388360 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:93 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2186
check_prev_add kernel/locking/lockdep.c:3133 [inline]
check_prevs_add kernel/locking/lockdep.c:3252 [inline]
validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868
__lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
down_read_killable+0xca/0xd30 kernel/locking/rwsem.c:1549
mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:153
get_mmap_lock_carefully mm/memory.c:5879 [inline]
lock_mm_and_find_vma+0x29c/0x2f0 mm/memory.c:5930
do_user_addr_fault arch/x86/mm/fault.c:1361 [inline]
handle_page_fault arch/x86/mm/fault.c:1481 [inline]
exc_page_fault+0x1bf/0x8c0 arch/x86/mm/fault.c:1539
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
RIP: 0010:fault_in_readable+0x108/0x2b0 mm/gup.c:2237
Code: 00 00 00 0f 01 cb 0f ae e8 48 89 de 48 81 e6 ff 0f 00 00 31 ff e8 48 af b7 ff 48 89 d8 48 25 ff 0f 00 00 4c 89 74 24 18 74 30 <8a> 1b e8 51 aa b7 ff 43 0f b6 04 2f 84 c0 0f 85 4d 01 00 00 88 5c
RSP: 0018:ffffc90003487a00 EFLAGS: 00050202
RAX: 0000000000000440 RBX: 0000000020005440 RCX: ffff88801cff8000
RDX: 0000000000000000 RSI: 0000000000000440 RDI: 0000000000000000
RBP: ffffc90003487ab8 R08: ffffffff81dbbb68 R09: ffffffff84a51eb9
R10: 0000000000000002 R11: ffff88801cff8000 R12: 000000000000000f
R13: dffffc0000000000 R14: 1ffff92000690f44 R15: 1ffff92000690f48
fault_in_iov_iter_readable+0x229/0x280 lib/iov_iter.c:94
generic_perform_write+0x29f/0x840 mm/filemap.c:4009
ntfs_file_write_iter+0x663/0x740 fs/ntfs3/file.c:1193
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xa72/0xc90 fs/read_write.c:590
ksys_write+0x1a0/0x2c0 fs/read_write.c:643
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: 0033:0x7f0a955a2c59
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0a95537218 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f0a9564a6d8 RCX: 00007f0a955a2c59
RDX: 000000000000000f RSI: 0000000020005440 RDI: 0000000000000004
RBP: 00007f0a9564a6d0 R08: 00007ffdf6185d97 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0a95616830
R13: 0000000000000016 R14: 7275632e73646970 R15: 69662f7375622f2e
</TASK>
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 0f add %cl,(%rdi)
4: 01 cb add %ecx,%ebx
6: 0f ae e8 lfence
9: 48 89 de mov %rbx,%rsi
c: 48 81 e6 ff 0f 00 00 and $0xfff,%rsi
13: 31 ff xor %edi,%edi
15: e8 48 af b7 ff call 0xffb7af62
1a: 48 89 d8 mov %rbx,%rax
1d: 48 25 ff 0f 00 00 and $0xfff,%rax
23: 4c 89 74 24 18 mov %r14,0x18(%rsp)
28: 74 30 je 0x5a
* 2a: 8a 1b mov (%rbx),%bl <-- trapping instruction
2c: e8 51 aa b7 ff call 0xffb7aa82
31: 43 0f b6 04 2f movzbl (%r15,%r13,1),%eax
36: 84 c0 test %al,%al
38: 0f 85 4d 01 00 00 jne 0x18b
3e: 88 .byte 0x88
3f: 5c pop %rsp

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