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BUG: KASAN: null-ptr-deref in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: null-ptr-deref in refcount_sub_and_test_checked+0x9d/0x310 lib/refcount.c:179
Read of size 4 at addr 0000000000000020 by task syz-executor1/9067

CPU: 0 PID: 9067 Comm: syz-executor1 Not tainted 4.20.0-rc7+ #280
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x244/0x39d lib/dump_stack.c:113
 kasan_report_error mm/kasan/report.c:352 [inline]
 kasan_report.cold.8+0x6d/0x309 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 refcount_sub_and_test_checked+0x9d/0x310 lib/refcount.c:179
 refcount_dec_and_test_checked+0x1a/0x20 lib/refcount.c:212
 vb2_vmalloc_put+0x19/0x80 drivers/media/common/videobuf2/videobuf2-vmalloc.c:68
 __vb2_buf_mem_free+0x112/0x210 drivers/media/common/videobuf2/videobuf2-core.c:242
 __vb2_free_mem drivers/media/common/videobuf2/videobuf2-core.c:413 [inline]
 __vb2_queue_free+0x830/0xa30 drivers/media/common/videobuf2/videobuf2-core.c:458
 vb2_core_queue_release+0x62/0x80 drivers/media/common/videobuf2/videobuf2-core.c:2257
 vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:842 [inline]
 _vb2_fop_release+0x1d2/0x2b0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1015
 vb2_fop_release+0x77/0xc0 drivers/media/common/videobuf2/videobuf2-v4l2.c:1029
 vivid_fop_release+0x18e/0x440 drivers/media/platform/vivid/vivid-core.c:474
 v4l2_release+0x224/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:456
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_32_irqs_on arch/x86/entry/common.c:341 [inline]
 do_fast_syscall_32+0xcd5/0xfb2 arch/x86/entry/common.c:397
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fb1a29
Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:000000000845fdac EFLAGS: 00000216 ORIG_RAX: 0000000000000006
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
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