Re: [syzbot] BUG: unable to handle kernel NULL pointer dereference in truncate_inode_pages_final

[Dmitry Vyukov]

On Sat, 1 Oct 2022 at 15:42, syzbot
<syzbot+3209de1c96568282edc6@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    3800a713b607 Merge tag 'mm-hotfixes-stable-2022-09-26' of ..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=119b63ef080000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a1992c90769e07
> dashboard link: https://syzkaller.appspot.com/bug?extid=3209de1c96568282edc6
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/0012f6c5db09/disk-3800a713.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/6c2ba89f2218/vmlinux-3800a713.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+3209de1c96568282edc6@xxxxxxxxxxxxxxxxxxxxxxxxx

+ntfs3 maintainers

> ntfs3: loop5: Different NTFS' sector size (1024) and media sector size (512)
> ntfs3: loop5: RAW NTFS volume: Filesystem size 0.00 Gb > volume size 0.00 Gb. Mount in read-only
> BUG: kernel NULL pointer dereference, address: 000000000000002b
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 7b94f067 P4D 7b94f067 PUD 21ad8067 PMD 0
> Oops: 0000 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 15950 Comm: syz-executor.5 Not tainted 6.0.0-rc7-syzkaller-00029-g3800a713b607 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
> RIP: 0010:__lock_release kernel/locking/lockdep.c:5350 [inline]
> RIP: 0010:lock_release+0x22c/0x780 kernel/locking/lockdep.c:5686
> Code: 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 a7 04 00 00 <8b> 73 24 85 f6 0f 85 66 04 00 00 48 8d 7b 22 48 b8 00 00 00 00 00
> RSP: 0018:ffffc90014787a10 EFLAGS: 00010046
> RAX: 0000000000000007 RBX: 0000000000000007 RCX: ffffc90014787a60
> RDX: 0000000000000000 RSI: ffff888072fb0518 RDI: ffff888039842ac4
> RBP: 1ffff920028f0f44 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: ffff888072fb0518
> R13: 0000000000000002 R14: ffff888039842a70 R15: ffff888039842000
> FS:  00007f7638dfe700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000000002b CR3: 00000000281a9000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:157 [inline]
>  _raw_spin_unlock_irq+0x12/0x40 kernel/locking/spinlock.c:202
>  spin_unlock_irq include/linux/spinlock.h:399 [inline]
>  truncate_inode_pages_final+0x5f/0x80 mm/truncate.c:484
>  ntfs_evict_inode+0x16/0xa0 fs/ntfs3/inode.c:1741
>  evict+0x2ed/0x6b0 fs/inode.c:665
>  iput_final fs/inode.c:1748 [inline]
>  iput.part.0+0x55d/0x810 fs/inode.c:1774
>  iput+0x58/0x70 fs/inode.c:1764
>  ntfs_fill_super+0x2e89/0x37f0 fs/ntfs3/super.c:1190
>  get_tree_bdev+0x440/0x760 fs/super.c:1323
>  vfs_get_tree+0x89/0x2f0 fs/super.c:1530
>  do_new_mount fs/namespace.c:3040 [inline]
>  path_mount+0x1326/0x1e20 fs/namespace.c:3370
>  do_mount fs/namespace.c:3383 [inline]
>  __do_sys_mount fs/namespace.c:3591 [inline]
>  __se_sys_mount fs/namespace.c:3568 [inline]
>  __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f7639e8bb9a
> Code: 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 b8 04 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 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:00007f7638dfdf88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 0000000020000580 RCX: 00007f7639e8bb9a
> RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f7638dfdfe0
> RBP: 00007f7638dfe020 R08: 00007f7638dfe020 R09: 0000000020000000
> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
> R13: 0000000020000100 R14: 00007f7638dfdfe0 R15: 0000000020000040
>  </TASK>
> Modules linked in:
> CR2: 000000000000002b
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__lock_release kernel/locking/lockdep.c:5350 [inline]
> RIP: 0010:lock_release+0x22c/0x780 kernel/locking/lockdep.c:5686
> Code: 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 a7 04 00 00 <8b> 73 24 85 f6 0f 85 66 04 00 00 48 8d 7b 22 48 b8 00 00 00 00 00
> RSP: 0018:ffffc90014787a10 EFLAGS: 00010046
> RAX: 0000000000000007 RBX: 0000000000000007 RCX: ffffc90014787a60
> RDX: 0000000000000000 RSI: ffff888072fb0518 RDI: ffff888039842ac4
> RBP: 1ffff920028f0f44 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: ffff888072fb0518
> R13: 0000000000000002 R14: ffff888039842a70 R15: ffff888039842000
> FS:  00007f7638dfe700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000000000000002b CR3: 00000000281a9000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0:   48 b8 00 00 00 00 00    movabs $0xdffffc0000000000,%rax
>    7:   fc ff df
>    a:   48 89 fa                mov    %rdi,%rdx
>    d:   48 c1 ea 03             shr    $0x3,%rdx
>   11:   0f b6 14 02             movzbl (%rdx,%rax,1),%edx
>   15:   48 89 f8                mov    %rdi,%rax
>   18:   83 e0 07                and    $0x7,%eax
>   1b:   83 c0 03                add    $0x3,%eax
>   1e:   38 d0                   cmp    %dl,%al
>   20:   7c 08                   jl     0x2a
>   22:   84 d2                   test   %dl,%dl
>   24:   0f 85 a7 04 00 00       jne    0x4d1
> * 2a:   8b 73 24                mov    0x24(%rbx),%esi <-- trapping instruction
>   2d:   85 f6                   test   %esi,%esi
>   2f:   0f 85 66 04 00 00       jne    0x49b
>   35:   48 8d 7b 22             lea    0x22(%rbx),%rdi
>   39:   48                      rex.W
>   3a:   b8 00 00 00 00          mov    $0x0,%eax
>
>
> ---
> This report is generated by a bot. It may contain errors.
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> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
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