BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 71e3e067 P4D 71e3e067 PUD 5ee87067 PMD 0 
Oops: Oops: 0010 [#1] SMP KASAN NOPTI
CPU: 1 UID: 0 PID: 10793 Comm: syz.3.1337 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: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0000:ffffc90000bf79c8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888029ba8830 RCX: ffffc900277b9000
RDX: 0000000000080000 RSI: ffffffff82c2df7c RDI: ffff888029ba8780
RBP: 000000000013d200 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888029ba8818
R13: dffffc0000000000 R14: ffff888029ba8780 R15: ffff88807135cb40
FS:  0000000000000000(0000) GS:ffff888097246000(0063) knlGS:00000000f53c4b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000071e3f000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 netfs_unbuffered_write+0xae5/0x2080 fs/netfs/direct_write.c:189
 netfs_unbuffered_write_iter_locked+0x801/0xab0 fs/netfs/direct_write.c:287
 netfs_unbuffered_write_iter+0x40c/0x710 fs/netfs/direct_write.c:377
 v9fs_file_write_iter+0xbf/0x100 fs/9p/vfs_file.c:409
 do_iter_readv_writev+0x6ee/0x920 fs/read_write.c:829
 vfs_writev+0x360/0xe10 fs/read_write.c:1059
 do_writev+0x13e/0x340 fs/read_write.c:1105
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xe3/0x8c0 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7f42f6c
Code: d2 74 05 c1 e8 0c 89 02 8b 5d fc 31 c0 c9 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 2e 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 58 b8
RSP: 002b:00000000f53c450c EFLAGS: 00000292 ORIG_RAX: 0000000000000092
RAX: ffffffffffffffda RBX: 000000000000000a RCX: 0000000080000a40
RDX: 0000000000000021 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0000:ffffc90000bf79c8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888029ba8830 RCX: ffffc900277b9000
RDX: 0000000000080000 RSI: ffffffff82c2df7c RDI: ffff888029ba8780
RBP: 000000000013d200 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffff888029ba8818
R13: dffffc0000000000 R14: ffff888029ba8780 R15: ffff88807135cb40
FS:  0000000000000000(0000) GS:ffff888097246000(0063) knlGS:00000000f53c4b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000071e3f000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	d2 74 05 c1          	shlb   %cl,-0x3f(%rbp,%rax,1)
   4:	e8 0c 89 02 8b       	call   0x8b028915
   9:	5d                   	pop    %rbp
   a:	fc                   	cld
   b:	31 c0                	xor    %eax,%eax
   d:	c9                   	leave
   e:	c3                   	ret
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	90                   	nop
  18:	90                   	nop
  19:	90                   	nop
  1a:	90                   	nop
  1b:	90                   	nop
  1c:	90                   	nop
  1d:	90                   	nop
  1e:	0f 1f 00             	nopl   (%rax)
  21:	51                   	push   %rcx
  22:	52                   	push   %rdx
  23:	55                   	push   %rbp
  24:	89 e5                	mov    %esp,%ebp
  26:	0f 34                	sysenter
  28:	cd 80                	int    $0x80
* 2a:	5d                   	pop    %rbp <-- trapping instruction
  2b:	5a                   	pop    %rdx
  2c:	59                   	pop    %rcx
  2d:	c3                   	ret
  2e:	90                   	nop
  2f:	2e 8d b4 26 00 00 00 	cs lea 0x0(%rsi,%riz,1),%esi
  36:	00
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  3e:	58                   	pop    %rax
  3f:	b8                   	.byte 0xb8