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: 7990 Comm: syz-executor115 Not tainted 4.14.292-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
task: ffff888097014180 task.stack: ffff8880a2480000
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:ffff8880a2487b48 EFLAGS: 00010297
RAX: ffff888097014180 RBX: ffff8880a235ca00 RCX: 1ffff11012e0294a
RDX: 0000000000000000 RSI: ffff888097014a30 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff8880a235ca14 R14: 0000000000000000 R15: ffffffff84c20ac0
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
 vb2_queue_release drivers/media/v4l2-core/videobuf2-v4l2.c:669 [inline]
 _vb2_fop_release+0x1c1/0x280 drivers/media/v4l2-core/videobuf2-v4l2.c:840
 vivid_fop_release+0x17d/0x6c0 drivers/media/platform/vivid/vivid-core.c:486
 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+0x46/0xbb
RIP: 0033:0x7fd48482e469
RSP: 002b:00007fff674c2848 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007fd4848a2270 RCX: 00007fd48482e469
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd4848a2270
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
Code: e9 ca fc ff ff e8 88 f3 bc fc e9 96 fc ff ff e8 ae f5 bc fc e9 fd fe ff ff 66 0f 1f 84 00 00 00 00 00 55 48 89 fd e8 f7 3c 93 fc <f0> ff 4d 20 0f 88 3d c3 5f 02 74 06 5d e9 e5 3c 93 fc e8 e0 3c 
RIP: refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline] RSP: ffff8880a2487b48
RIP: vb2_vmalloc_put+0x9/0x60 drivers/media/v4l2-core/videobuf2-vmalloc.c:68 RSP: ffff8880a2487b48
CR2: 0000000000000020
---[ end trace 2f97ef3eda1f863d ]---
----------------
Code disassembly (best guess):
   0:	e9 ca fc ff ff       	jmpq   0xfffffccf
   5:	e8 88 f3 bc fc       	callq  0xfcbcf392
   a:	e9 96 fc ff ff       	jmpq   0xfffffca5
   f:	e8 ae f5 bc fc       	callq  0xfcbcf5c2
  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 f7 3c 93 fc       	callq  0xfc933d22
* 2b:	f0 ff 4d 20          	lock decl 0x20(%rbp) <-- trapping instruction
  2f:	0f 88 3d c3 5f 02    	js     0x25fc372
  35:	74 06                	je     0x3d
  37:	5d                   	pop    %rbp
  38:	e9 e5 3c 93 fc       	jmpq   0xfc933d22
  3d:	e8                   	.byte 0xe8
  3e:	e0 3c                	loopne 0x7c