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: 0 PID: 7954 Comm: syz-executor245 Not tainted 4.14.302-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 task: ffff8880b34ca000 task.stack: ffff8880b3a18000 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:ffff8880b3a1fb98 EFLAGS: 00010297 RAX: ffff8880b34ca000 RBX: ffff8880981a3080 RCX: 1ffff1101669951a RDX: 0000000000000000 RSI: ffff8880b34ca8b0 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880981a3094 R14: 0000000000000000 R15: ffffffff84c281a0 FS: 0000555555a87300(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000020 CR3: 0000000008e6a000 CR4: 00000000003406f0 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: 0033:0x7f6d897f4f19 RSP: 002b:00007fff57ab1328 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f6d89869270 RCX: 00007f6d897f4f19 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6d89869270 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: ffff8880b3a1fb98 RIP: vb2_vmalloc_put+0x9/0x60 drivers/media/v4l2-core/videobuf2-vmalloc.c:68 RSP: ffff8880b3a1fb98 CR2: 0000000000000020 ---[ end trace 899a3b6de3ea3550 ]--- ---------------- 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