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 9c229067 P4D 9c229067 PUD a6233067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 29125 Comm: syz-executor.4 Not tainted 4.14.214-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff88808f5fe100 task.stack: ffff8880a3318000
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:ffff8880a331fc58 EFLAGS: 00010297
RAX: ffff88808f5fe100 RBX: ffff888093fefcc0 RCX: 1ffff11011ebfd3a
RDX: 0000000000000000 RSI: ffff88808f5fe9b0 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff888093fefcd4 R14: 0000000000000000 R15: ffffffff84d23740
FS:  0000000001a38940(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000020 CR3: 00000000b11d5000 CR4: 00000000001406e0
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:2043
 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/0x6b6 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
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x417b71
RSP: 002b:00007ffe2d6acf40 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000417b71
RDX: 0000001b2fa20000 RSI: 0000000080000000 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000256 R09: 0000000054bb625a
R10: 00007ffe2d6ad020 R11: 0000000000000293 R12: ffffffffffffffff
R13: 00000000001a86bb R14: 00000000000003e8 R15: 000000000119bf8c
Code: e9 ca fc ff ff e8 e8 f5 ae fc e9 96 fc ff ff e8 0e f8 ae fc e9 fd fe ff ff 66 0f 1f 84 00 00 00 00 00 55 48 89 fd e8 47 09 85 fc <f0> ff 4d 20 0f 88 42 33 4c 02 74 06 5d e9 35 09 85 fc e8 30 09 
RIP: refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline] RSP: ffff8880a331fc58
RIP: vb2_vmalloc_put+0x9/0x60 drivers/media/v4l2-core/videobuf2-vmalloc.c:68 RSP: ffff8880a331fc58
CR2: 0000000000000020
---[ end trace d35e89fadf0ac648 ]---