------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 0 PID: 8524 at lib/refcount.c:156 refcount_inc_checked+0x4b/0x50 lib/refcount.c:156
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 8524 Comm: syz-executor.0 Not tainted 5.4.0-rc7+ #0
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+0x1fb/0x318 lib/dump_stack.c:118
 panic+0x264/0x7a9 kernel/panic.c:221
 __warn+0x20e/0x210 kernel/panic.c:582
 report_bug+0x1b6/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 do_error_trap+0xd7/0x440 arch/x86/kernel/traps.c:272
 do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:291
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:refcount_inc_checked+0x4b/0x50 lib/refcount.c:156
Code: 3d b8 7e 75 05 01 75 08 e8 42 d6 2d fe 5b 5d c3 e8 3a d6 2d fe c6 05 a2 7e 75 05 01 48 c7 c7 a4 d9 40 88 31 c0 e8 e5 6c 00 fe <0f> 0b eb df 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 ec 10
RSP: 0018:ffff88802810f9a0 EFLAGS: 00010246
RAX: 1f39b68fcabe3e00 RBX: ffff888098d4a640 RCX: 0000000000040000
RDX: ffffc90006146000 RSI: 000000000000f804 RDI: 000000000000f805
RBP: ffff88802810f9a8 R08: ffffffff815cc074 R09: fffffbfff12bc2a8
R10: fffffbfff12bc2a8 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888098d4a608 R14: ffff888098d4a644 R15: ffff888098d4a608
 kref_get include/linux/kref.h:45 [inline]
 kobject_get+0x91/0xc0 lib/kobject.c:644
 cdev_get fs/char_dev.c:355 [inline]
 chrdev_open+0x17e/0x590 fs/char_dev.c:400
 do_dentry_open+0x740/0x10c0 fs/open.c:797
 vfs_open+0x73/0x80 fs/open.c:914
 do_last fs/namei.c:3408 [inline]
 path_openat+0x1397/0x4420 fs/namei.c:3525
 do_filp_open+0x192/0x3d0 fs/namei.c:3555
 do_sys_open+0x29f/0x560 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x87/0x90 fs/open.c:1110
 do_syscall_64+0xf7/0x1c0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4143d1
Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 19 00 00 c3 48 83 ec 08 e8 0a fa ff ff 48 89 04 24 b8 02 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fa ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f4d5d7087a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 00000000004143d1
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f4d5d708850
RBP: 000000000075bfc8 R08: 000000000000000f R09: 0000000000000000
R10: 00007f4d5d7099d0 R11: 0000000000000293 R12: 00007f4d5d7096d4
R13: 00000000004ca143 R14: 00000000004e1eb0 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..