kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 PID: 4329 Comm: gfs2_quotad Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:do_sync+0x8e0/0xba0 fs/gfs2/quota.c:986
Code: 8d 9d b8 04 00 00 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 0e 17 4e fe 48 8b 1b 48 8d 7b 10 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 f4 16 4e fe 48 8b 7b 10 48 89 de ba 02 00
RSP: 0018:ffffc90004ab7b80 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000000 RCX: f82fb9aa0c4e2400
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000010
RBP: ffffc90004ab7ce8 R08: ffffffff901cb1ef R09: 1ffffffff203963d
R10: dffffc0000000000 R11: fffffbfff203963e R12: ffff8880234eff00
R13: ffff88805f013640 R14: 00000000fffffffb R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555593f5ab8 CR3: 00000000232c3000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 gfs2_quota_sync+0x355/0x780 fs/gfs2/quota.c:1329
 quotad_check_timeo fs/gfs2/quota.c:1519 [inline]
 gfs2_quotad+0x40f/0x890 fs/gfs2/quota.c:1586
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Modules linked in:
---[ end trace 609df2ee976f49b4 ]---
RIP: 0010:do_sync+0x8e0/0xba0 fs/gfs2/quota.c:986
Code: 8d 9d b8 04 00 00 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 0e 17 4e fe 48 8b 1b 48 8d 7b 10 48 89 f8 48 c1 e8 03 <42> 80 3c 38 00 74 05 e8 f4 16 4e fe 48 8b 7b 10 48 89 de ba 02 00
RSP: 0018:ffffc90004ab7b80 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000000 RCX: f82fb9aa0c4e2400
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000010
RBP: ffffc90004ab7ce8 R08: ffffffff901cb1ef R09: 1ffffffff203963d
R10: dffffc0000000000 R11: fffffbfff203963e R12: ffff8880234eff00
R13: ffff88805f013640 R14: 00000000fffffffb R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc454275fc0 CR3: 000000001f744000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	8d 9d b8 04 00 00    	lea    0x4b8(%rbp),%ebx
   6:	48 89 d8             	mov    %rbx,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1)
  12:	74 08                	je     0x1c
  14:	48 89 df             	mov    %rbx,%rdi
  17:	e8 0e 17 4e fe       	call   0xfe4e172a
  1c:	48 8b 1b             	mov    (%rbx),%rbx
  1f:	48 8d 7b 10          	lea    0x10(%rbx),%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f:	74 05                	je     0x36
  31:	e8 f4 16 4e fe       	call   0xfe4e172a
  36:	48 8b 7b 10          	mov    0x10(%rbx),%rdi
  3a:	48 89 de             	mov    %rbx,%rsi
  3d:	ba                   	.byte 0xba
  3e:	02 00                	add    (%rax),%al