Re: [syzbot] [gfs2?] general protection fault in gfs2_glock_dq (2)

[syzbot <syzbot+5a5f492ccae698fd7434@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    a975094bf98c Merge tag 'exfat-for-7.2-rc1' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=157bc2ae580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f5fece1a9477c321
dashboard link: https://syzkaller.appspot.com/bug?extid=5a5f492ccae698fd7434
compiler:       Debian clang version 22.1.6 (++20260514074242+fc4aad7b5db3-1~exp1~20260514074407.73), Debian LLD 22.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1391e566580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10e34d56580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-a975094b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3c6e219ebae0/vmlinux-a975094b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8ee0600dd547/bzImage-a975094b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b036c6932e75/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=12d95b7a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5a5f492ccae698fd7434@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4deac15fac R14: 00007f4deac15fa0 R15: 00007f4deac15fa0
 </TASK>
gfs2: fsid=syz:syz.0: about to withdraw this file system
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 0 UID: 0 PID: 5476 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
RIP: 0010:do_raw_spin_lock+0x73/0x2f0 kernel/locking/spinlock_debug.c:115
Code: c7 44 24 30 d0 83 a2 81 4c 8d 64 24 20 49 c1 ec 03 48 b8 f1 f1 f1 f1 f8 f3 f3 f3 49 89 04 14 4c 8d 77 04 4c 89 f0 48 c1 e8 03 <0f> b6 04 10 84 c0 0f 85 f3 01 00 00 41 8b 06 3d ad 4e ad de 0f 85
RSP: 0018:ffffc90003797a80 EFLAGS: 00010203
RAX: 0000000000000004 RBX: 0000000000000020 RCX: 0000000080000002
RDX: dffffc0000000000 RSI: ffffffff8c296400 RDI: 0000000000000020
RBP: ffffc90003797b30 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1007fdb805 R12: 1ffff920006f2f54
R13: 0000000000000000 R14: 0000000000000024 R15: dffffc0000000000
FS:  0000555585a45500(0000) GS:ffff88808c848000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000006cb000 CR3: 000000003e1b2000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 spin_lock include/linux/spinlock.h:342 [inline]
 gfs2_glock_dq+0xbe/0xb40 fs/gfs2/glock.c:1598
 gfs2_glock_dq_uninit+0x25/0xb0 fs/gfs2/glock.c:1656
 gfs2_seek_data+0x176/0x250 fs/gfs2/inode.c:2246
 gfs2_llseek+0x1c1/0x270 fs/gfs2/file.c:75
 vfs_llseek fs/read_write.c:391 [inline]
 ksys_lseek fs/read_write.c:404 [inline]
 __do_sys_lseek fs/read_write.c:414 [inline]
 __se_sys_lseek fs/read_write.c:412 [inline]
 __x64_sys_lseek+0x14f/0x1e0 fs/read_write.c:412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4dea99ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd2c1b0b78 EFLAGS: 00000246 ORIG_RAX: 0000000000000008
RAX: ffffffffffffffda RBX: 00007f4deac15fa0 RCX: 00007f4dea99ce59
RDX: 0000000000000003 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f4deaa32e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4deac15fac R14: 00007f4deac15fa0 R15: 00007f4deac15fa0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
RIP: 0010:do_raw_spin_lock+0x73/0x2f0 kernel/locking/spinlock_debug.c:115
Code: c7 44 24 30 d0 83 a2 81 4c 8d 64 24 20 49 c1 ec 03 48 b8 f1 f1 f1 f1 f8 f3 f3 f3 49 89 04 14 4c 8d 77 04 4c 89 f0 48 c1 e8 03 <0f> b6 04 10 84 c0 0f 85 f3 01 00 00 41 8b 06 3d ad 4e ad de 0f 85
RSP: 0018:ffffc90003797a80 EFLAGS: 00010203
RAX: 0000000000000004 RBX: 0000000000000020 RCX: 0000000080000002
RDX: dffffc0000000000 RSI: ffffffff8c296400 RDI: 0000000000000020
RBP: ffffc90003797b30 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1007fdb805 R12: 1ffff920006f2f54
R13: 0000000000000000 R14: 0000000000000024 R15: dffffc0000000000
FS:  0000555585a45500(0000) GS:ffff88808c848000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000006cb000 CR3: 000000003e1b2000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	c7 44 24 30 d0 83 a2 	movl   $0x81a283d0,0x30(%rsp)
   7:	81
   8:	4c 8d 64 24 20       	lea    0x20(%rsp),%r12
   d:	49 c1 ec 03          	shr    $0x3,%r12
  11:	48 b8 f1 f1 f1 f1 f8 	movabs $0xf3f3f3f8f1f1f1f1,%rax
  18:	f3 f3 f3
  1b:	49 89 04 14          	mov    %rax,(%r12,%rdx,1)
  1f:	4c 8d 77 04          	lea    0x4(%rdi),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	0f b6 04 10          	movzbl (%rax,%rdx,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	0f 85 f3 01 00 00    	jne    0x229
  36:	41 8b 06             	mov    (%r14),%eax
  39:	3d ad 4e ad de       	cmp    $0xdead4ead,%eax
  3e:	0f                   	.byte 0xf
  3f:	85                   	.byte 0x85


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