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

[Matthew Wilcox]

On Thu, Oct 20, 2022 at 06:25:43AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:

NTFS.  Ignored.

> HEAD commit:    55be6084c8e0 Merge tag 'timers-core-2022-10-05' of git://g..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=108783e6880000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c29b6436e994d72e
> dashboard link: https://syzkaller.appspot.com/bug?extid=e33c2a7e25ff31df5297
> compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, 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/c8f5131ab57d/disk-55be6084.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/77167f226f35/vmlinux-55be6084.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+e33c2a7e25ff31df5297@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> ntfs: volume version 3.1.
> BUG: kernel NULL pointer dereference, address: 0000000000000000
> #PF: supervisor instruction fetch in kernel mode
> #PF: error_code(0x0010) - not-present page
> PGD a5bf9067 P4D a5bf9067 PUD 37d2e067 PMD 0 
> Oops: 0010 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 11041 Comm: syz-executor.1 Not tainted 6.0.0-syzkaller-09589-g55be6084c8e0 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
> RIP: 0010:0x0
> Code: Unable to access opcode bytes at 0xffffffffffffffd6.
> RSP: 0018:ffffc9001504f618 EFLAGS: 00010287
> RAX: ffffffff81b64c0e RBX: ffffc9001504f680 RCX: 0000000000040000
> RDX: ffffc9000ae14000 RSI: ffffea0002a61580 RDI: 0000000000000000
> RBP: ffffc9001504f6f8 R08: dffffc0000000000 R09: fffff9400054c2b1
> R10: fffff9400054c2b1 R11: 1ffffd400054c2b0 R12: ffffea0002a61580
> R13: 1ffffd400054c2b1 R14: 0000000000000000 R15: ffffea0002a61588
> FS:  00007f0f425d5700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffffffffffffd6 CR3: 00000000a32e1000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  filemap_read_folio+0x1ba/0x7f0 mm/filemap.c:2399
>  do_read_cache_folio+0x2d3/0x790 mm/filemap.c:3526
>  do_read_cache_page mm/filemap.c:3568 [inline]
>  read_cache_page+0x57/0x250 mm/filemap.c:3577
>  read_mapping_page include/linux/pagemap.h:756 [inline]
>  ntfs_map_page fs/ntfs/aops.h:75 [inline]
>  ntfs_check_logfile+0x3f1/0x2a50 fs/ntfs/logfile.c:532
>  load_and_check_logfile+0x6f/0xd0 fs/ntfs/super.c:1215
>  load_system_files+0x3376/0x48d0 fs/ntfs/super.c:1941
>  ntfs_fill_super+0x19a9/0x2bf0 fs/ntfs/super.c:2892
>  mount_bdev+0x26c/0x3a0 fs/super.c:1400
>  legacy_get_tree+0xea/0x180 fs/fs_context.c:610
>  vfs_get_tree+0x88/0x270 fs/super.c:1530
>  do_new_mount+0x289/0xad0 fs/namespace.c:3040
>  do_mount fs/namespace.c:3383 [inline]
>  __do_sys_mount fs/namespace.c:3591 [inline]
>  __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3568
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f0f4148cada
> 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:00007f0f425d4f88 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 00007f0f4148cada
> RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007f0f425d4fe0
> RBP: 00007f0f425d5020 R08: 00007f0f425d5020 R09: 0000000020000000
> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000020000000
> R13: 0000000020000100 R14: 00007f0f425d4fe0 R15: 00000000200026c0
>  </TASK>
> Modules linked in:
> CR2: 0000000000000000
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:0x0
> Code: Unable to access opcode bytes at 0xffffffffffffffd6.
> RSP: 0018:ffffc9001504f618 EFLAGS: 00010287
> RAX: ffffffff81b64c0e RBX: ffffc9001504f680 RCX: 0000000000040000
> RDX: ffffc9000ae14000 RSI: ffffea0002a61580 RDI: 0000000000000000
> RBP: ffffc9001504f6f8 R08: dffffc0000000000 R09: fffff9400054c2b1
> R10: fffff9400054c2b1 R11: 1ffffd400054c2b0 R12: ffffea0002a61580
> R13: 1ffffd400054c2b1 R14: 0000000000000000 R15: ffffea0002a61588
> FS:  00007f0f425d5700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffffffffffffd6 CR3: 00000000a32e1000 CR4: 00000000003506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 
> 
> ---
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> 
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