[v6.1] general protection fault in __find_get_block

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dcbcab9d7079 Linux 6.1.174
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=145ee52e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4dd3c1715f0a309b
dashboard link: https://syzkaller.appspot.com/bug?extid=9c5a581093bc5e88a089
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0f3e0db767ff/disk-dcbcab9d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d14e7b82c164/vmlinux-dcbcab9d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/52745da582ab/bzImage-dcbcab9d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9c5a58...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
CPU: 1 PID: 4278 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:__find_get_block_slow fs/buffer.c:191 [inline]
RIP: 0010:__find_get_block+0x2e2/0xec0 fs/buffer.c:1307
Code: d8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 8b 44 24 28 48 8d 58 30 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 20 85 e2 ff 4c 8b 23 49 8d 7c 24 30
RSP: 0018:ffffc90003e07660 EFLAGS: 00010206
RAX: 0000000000000006 RBX: 0000000000000030 RCX: dffffc0000000000
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf1b60
RBP: ffffc90003e07798 R08: ffffffff90afd39f R09: 1ffffffff215fa73
R10: dffffc0000000000 R11: fffffbfff215fa74 R12: fffffffffffffff1
R13: 0000000000000000 R14: 0000000000036af0 R15: 000000000000004c
FS: 000055558bb1b500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb7b0dab000 CR3: 000000005cc86000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
jbd2_journal_cancel_revoke+0x3e2/0x470 fs/jbd2/revoke.c:469
do_get_write_access+0xb4f/0xf60 fs/jbd2/transaction.c:1160
jbd2_journal_get_write_access+0x108/0x140 fs/jbd2/transaction.c:1250
__ocfs2_journal_access+0x4de/0x8c0 fs/ocfs2/journal.c:727
ocfs2_shutdown_local_alloc+0x428/0xaa0 fs/ocfs2/localalloc.c:432
ocfs2_dismount_volume+0x1ff/0x940 fs/ocfs2/super.c:1882
generic_shutdown_super+0x130/0x340 fs/super.c:501
kill_block_super+0x7c/0xe0 fs/super.c:1470
deactivate_locked_super+0x93/0xf0 fs/super.c:332
cleanup_mnt+0x42c/0x4b0 fs/namespace.c:1191
task_work_run+0x1d0/0x260 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f801ef9e097
Code: a2 c7 05 5c 06 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffe6b4db428 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f801f0321ca RCX: 00007f801ef9e097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe6b4db4e0
RBP: 00007ffe6b4db4e0 R08: 00007ffe6b4dc4e0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe6b4dc570
R13: 00007f801f0321ca R14: 000000000003b36a R15: 00007ffe6b4dc5b0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__find_get_block_slow fs/buffer.c:191 [inline]
RIP: 0010:__find_get_block+0x2e2/0xec0 fs/buffer.c:1307
Code: d8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 48 8b 44 24 28 48 8d 58 30 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 20 85 e2 ff 4c 8b 23 49 8d 7c 24 30
RSP: 0018:ffffc90003e07660 EFLAGS: 00010206
RAX: 0000000000000006 RBX: 0000000000000030 RCX: dffffc0000000000
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf1b60
RBP: ffffc90003e07798 R08: ffffffff90afd39f R09: 1ffffffff215fa73
R10: dffffc0000000000 R11: fffffbfff215fa74 R12: fffffffffffffff1
R13: 0000000000000000 R14: 0000000000036af0 R15: 000000000000004c
FS: 000055558bb1b500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4095bea2f8 CR3: 000000005cc86000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: d8 48 8d fmuls -0x73(%rax)
3: 65 d8 5b 41 fcomps %gs:0x41(%rbx)
7: 5c pop %rsp
8: 41 5d pop %r13
a: 41 5e pop %r14
c: 41 5f pop %r15
e: 5d pop %rbp
f: c3 ret
10: 48 8b 44 24 28 mov 0x28(%rsp),%rax
15: 48 8d 58 30 lea 0x30(%rax),%rbx
19: 48 89 d8 mov %rbx,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 48 89 df mov %rbx,%rdi
33: e8 20 85 e2 ff call 0xffe28558
38: 4c 8b 23 mov (%rbx),%r12
3b: 49 8d 7c 24 30 lea 0x30(%r12),%rdi


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