syzbot

loop0: detected capacity change from 0 to 32768
gfs2: fsid=syz:syz: Trying to join cluster "lock_nolock", "syz:syz"
gfs2: fsid=syz:syz: Now mounting FS (format 1801)...
gfs2: fsid=syz:syz.0: journal 0 mapped with 1 extents in 0ms
gfs2: fsid=syz:syz.0: first mount done, others may mount
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 UID: 0 PID: 5325 Comm: syz.0.0 Not tainted 6.14.0-rc6-syzkaller-00016-g0fed89a961ea #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:gfs2_glock_dq+0x4d/0xa60 fs/gfs2/glock.c:1664
Code: fd 4d 8d 65 10 4c 89 e5 48 c1 ed 03 80 7c 1d 00 00 74 08 4c 89 e7 e8 b2 1a 11 fe 49 8b 0c 24 4c 8d 79 10 4d 89 fe 49 c1 ee 03 <41> 80 3c 1e 00 74 0e 48 89 cb 4c 89 ff e8 91 1a 11 fe 48 89 d9 48
RSP: 0018:ffffc9000d4e7c38 EFLAGS: 00010202
RAX: ffffffff84180a04 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffffc9000ecca000 RSI: 0000000000000033 RDI: 0000000000000034
RBP: 1ffff92001a9cfa6 R08: ffff8880534bf4f3 R09: 1ffff1100a697e9e
R10: dffffc0000000000 R11: ffffed100a697e9f R12: ffffc9000d4e7d30
R13: ffffc9000d4e7d20 R14: 0000000000000002 R15: 0000000000000010
FS:  00007fb6473f56c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb63fdff000 CR3: 0000000043fc0000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 gfs2_glock_dq_uninit+0x25/0xb0 fs/gfs2/glock.c:1722
 gfs2_seek_hole+0x16c/0x240 fs/gfs2/inode.c:2151
 gfs2_llseek+0x11e/0x280 fs/gfs2/file.c:79
 vfs_llseek fs/read_write.c:382 [inline]
 ksys_lseek fs/read_write.c:395 [inline]
 __do_sys_lseek fs/read_write.c:405 [inline]
 __se_sys_lseek fs/read_write.c:403 [inline]
 __x64_sys_lseek+0x14c/0x1e0 fs/read_write.c:403
 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: 0033:0x7fb64af8d169
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb6473f5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000008
RAX: ffffffffffffffda RBX: 00007fb64b1a5fa0 RCX: 00007fb64af8d169
RDX: 0000000000000004 RSI: 0000000000000005 RDI: 0000000000000005
RBP: 00007fb64b00e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb64b1a5fa0 R15: 00007ffc3180fa28
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:gfs2_glock_dq+0x4d/0xa60 fs/gfs2/glock.c:1664
Code: fd 4d 8d 65 10 4c 89 e5 48 c1 ed 03 80 7c 1d 00 00 74 08 4c 89 e7 e8 b2 1a 11 fe 49 8b 0c 24 4c 8d 79 10 4d 89 fe 49 c1 ee 03 <41> 80 3c 1e 00 74 0e 48 89 cb 4c 89 ff e8 91 1a 11 fe 48 89 d9 48
RSP: 0018:ffffc9000d4e7c38 EFLAGS: 00010202
RAX: ffffffff84180a04 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffffc9000ecca000 RSI: 0000000000000033 RDI: 0000000000000034
RBP: 1ffff92001a9cfa6 R08: ffff8880534bf4f3 R09: 1ffff1100a697e9e
R10: dffffc0000000000 R11: ffffed100a697e9f R12: ffffc9000d4e7d30
R13: ffffc9000d4e7d20 R14: 0000000000000002 R15: 0000000000000010
FS:  00007fb6473f56c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb63fdff000 CR3: 0000000043fc0000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	fd                   	std
   1:	4d 8d 65 10          	lea    0x10(%r13),%r12
   5:	4c 89 e5             	mov    %r12,%rbp
   8:	48 c1 ed 03          	shr    $0x3,%rbp
   c:	80 7c 1d 00 00       	cmpb   $0x0,0x0(%rbp,%rbx,1)
  11:	74 08                	je     0x1b
  13:	4c 89 e7             	mov    %r12,%rdi
  16:	e8 b2 1a 11 fe       	call   0xfe111acd
  1b:	49 8b 0c 24          	mov    (%r12),%rcx
  1f:	4c 8d 79 10          	lea    0x10(%rcx),%r15
  23:	4d 89 fe             	mov    %r15,%r14
  26:	49 c1 ee 03          	shr    $0x3,%r14
* 2a:	41 80 3c 1e 00       	cmpb   $0x0,(%r14,%rbx,1) <-- trapping instruction
  2f:	74 0e                	je     0x3f
  31:	48 89 cb             	mov    %rcx,%rbx
  34:	4c 89 ff             	mov    %r15,%rdi
  37:	e8 91 1a 11 fe       	call   0xfe111acd
  3c:	48 89 d9             	mov    %rbx,%rcx
  3f:	48                   	rex.W