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 9f47b067 P4D 9f47b067 PUD ab698067 PMD 0 Oops: 0002 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 1 PID: 9488 Comm: syz-executor.5 Not tainted 4.14.282-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880932da540 task.stack: ffff88804c7c8000 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:ffff88804c7cfc58 EFLAGS: 00010297 RAX: ffff8880932da540 RBX: ffff8880a0c8ed00 RCX: 1ffff1101265b5c2 RDX: 0000000000000000 RSI: ffff8880932dadf0 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880a0c8ed14 R14: 0000000000000000 R15: ffffffff84c26cd0 FS: 0000555556418400(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000020 CR3: 000000009fedb000 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 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: 0033:0x7fea8dc39d4b RSP: 002b:00007ffd49262020 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007fea8dc39d4b RDX: 00007fea8dd9e508 RSI: ffffffffffffffff RDI: 0000000000000003 RBP: 00007fea8dd9b960 R08: 0000000000000000 R09: 00007fea8dd9e510 R10: 00007ffd49262120 R11: 0000000000000293 R12: 000000000002c1c8 R13: 00007ffd49262120 R14: 00007fea8dd9a030 R15: 0000000000000032 Code: e9 ca fc ff ff e8 88 92 bc fc e9 96 fc ff ff e8 ae 94 bc fc e9 fd fe ff ff 66 0f 1f 84 00 00 00 00 00 55 48 89 fd e8 c7 d9 92 fc <f0> ff 4d 20 0f 88 e9 a0 5f 02 74 06 5d e9 b5 d9 92 fc e8 b0 d9 RIP: refcount_dec_and_test arch/x86/include/asm/refcount.h:75 [inline] RSP: ffff88804c7cfc58 RIP: vb2_vmalloc_put+0x9/0x60 drivers/media/v4l2-core/videobuf2-vmalloc.c:68 RSP: ffff88804c7cfc58 CR2: 0000000000000020 ---[ end trace b9cd309f0ffe2a4c ]--- ---------------- Code disassembly (best guess): 0: e9 ca fc ff ff jmpq 0xfffffccf 5: e8 88 92 bc fc callq 0xfcbc9292 a: e9 96 fc ff ff jmpq 0xfffffca5 f: e8 ae 94 bc fc callq 0xfcbc94c2 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 c7 d9 92 fc callq 0xfc92d9f2 * 2b: f0 ff 4d 20 lock decl 0x20(%rbp) <-- trapping instruction 2f: 0f 88 e9 a0 5f 02 js 0x25fa11e 35: 74 06 je 0x3d 37: 5d pop %rbp 38: e9 b5 d9 92 fc jmpq 0xfc92d9f2 3d: e8 .byte 0xe8 3e: b0 d9 mov $0xd9,%al