BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
IP: refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline]
IP: vb2_vmalloc_put+0x9/0x60 drivers/media/v4l2-core/videobuf2-vmalloc.c:68
PGD 0 P4D 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 7970 Comm: syz-executor118 Not tainted 4.14.302-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
task: ffff8880b3a6a300 task.stack: ffff88808d528000
RIP: 0010:refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline]
RIP: 0010:vb2_vmalloc_put+0x9/0x60 drivers/media/v4l2-core/videobuf2-vmalloc.c:68
RSP: 0018:ffff88808d52fb98 EFLAGS: 00010297
RAX: ffff8880b3a6a300 RBX: ffff8880a4b94d40 RCX: 1ffff1101674d57a
RDX: 0000000000000000 RSI: ffff8880b3a6abb0 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8880a4b94d54 R14: 0000000000000000 R15: ffffffff84c281a0
FS:  0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000020 CR3: 0000000008e6a000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __vb2_buf_mem_free+0xfa/0x1d0 drivers/media/v4l2-core/videobuf2-core.c:240
 __vb2_free_mem drivers/media/v4l2-core/videobuf2-core.c:409 [inline]
 __vb2_queue_free+0x60d/0x7a0 drivers/media/v4l2-core/videobuf2-core.c:454
 vb2_core_queue_release+0x5b/0x70 drivers/media/v4l2-core/videobuf2-core.c:2054
 v4l2_m2m_ctx_release+0x26/0x30 drivers/media/v4l2-core/v4l2-mem2mem.c:702
 vim2m_release+0xd4/0x120 drivers/media/platform/vim2m.c:959
 v4l2_release+0xf4/0x190 drivers/media/v4l2-core/v4l2-dev.c:446
 __fput+0x25f/0x7a0 fs/file_table.c:210
 task_work_run+0x11f/0x190 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0xa44/0x2850 kernel/exit.c:868
 do_group_exit+0x100/0x2e0 kernel/exit.c:965
 SYSC_exit_group kernel/exit.c:976 [inline]
 SyS_exit_group+0x19/0x20 kernel/exit.c:974
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x5e/0xd3
RIP: 0033:0x7f8adb043f19
RSP: 002b:00007ffd4b3dac68 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f8adb0b8270 RCX: 00007f8adb043f19
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8adb0b8270
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
Code: e9 ca fc ff ff e8 b8 99 bc fc e9 96 fc ff ff e8 de 9b bc fc e9 fd fe ff ff 66 0f 1f 84 00 00 00 00 00 55 48 89 fd e8 97 d8 92 fc <f0> ff 4d 20 0f 88 f0 d9 5f 02 74 06 5d e9 85 d8 92 fc e8 80 d8 
RIP: refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline] RSP: ffff88808d52fb98
RIP: vb2_vmalloc_put+0x9/0x60 drivers/media/v4l2-core/videobuf2-vmalloc.c:68 RSP: ffff88808d52fb98
CR2: 0000000000000020
---[ end trace 8534a613c3f7056b ]---
----------------
Code disassembly (best guess):
   0:	e9 ca fc ff ff       	jmpq   0xfffffccf
   5:	e8 b8 99 bc fc       	callq  0xfcbc99c2
   a:	e9 96 fc ff ff       	jmpq   0xfffffca5
   f:	e8 de 9b bc fc       	callq  0xfcbc9bf2
  14:	e9 fd fe ff ff       	jmpq   0xffffff16
  19:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
  20:	00 00
  22:	55                   	push   %rbp
  23:	48 89 fd             	mov    %rdi,%rbp
  26:	e8 97 d8 92 fc       	callq  0xfc92d8c2
* 2b:	f0 ff 4d 20          	lock decl 0x20(%rbp) <-- trapping instruction
  2f:	0f 88 f0 d9 5f 02    	js     0x25fda25
  35:	74 06                	je     0x3d
  37:	5d                   	pop    %rbp
  38:	e9 85 d8 92 fc       	jmpq   0xfc92d8c2
  3d:	e8                   	.byte 0xe8
  3e:	80                   	.byte 0x80
  3f:	d8                   	.byte 0xd8