------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 1 PID: 19721 at lib/refcount.c:156 refcount_inc_checked lib/refcount.c:156 [inline]
WARNING: CPU: 1 PID: 19721 at lib/refcount.c:156 refcount_inc_checked+0x61/0x70 lib/refcount.c:154
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 19721 Comm: syz-executor.4 Not tainted 5.4.0-rc2-next-20191010 #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+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1028
RIP: 0010:refcount_inc_checked lib/refcount.c:156 [inline]
RIP: 0010:refcount_inc_checked+0x61/0x70 lib/refcount.c:154
Code: 1d 9b 2a 80 06 31 ff 89 de e8 9b f1 30 fe 84 db 75 dd e8 52 f0 30 fe 48 c7 c7 e0 85 e6 87 c6 05 7b 2a 80 06 01 e8 77 35 02 fe <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41
RSP: 0018:ffff88809ff878b8 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000015763 RSI: ffffffff815cb3a6 RDI: ffffed1013ff0f09
RBP: ffff88809ff878c8 R08: ffff888057aba100 R09: ffffed1015d26161
R10: ffffed1015d26160 R11: ffff8880ae930b07 R12: ffff8880634fc660
R13: 0000000000000000 R14: ffff88806d919780 R15: ffff888061f0b490
 kref_get include/linux/kref.h:45 [inline]
 kobject_get+0x66/0xc0 lib/kobject.c:644
 cdev_get+0x60/0xb0 fs/char_dev.c:355
 chrdev_open+0xb0/0x6b0 fs/char_dev.c:400
 do_dentry_open+0x4df/0x1250 fs/open.c:797
 vfs_open+0xa0/0xd0 fs/open.c:914
 do_last fs/namei.c:3412 [inline]
 path_openat+0x10e4/0x4710 fs/namei.c:3529
 do_filp_open+0x1a1/0x280 fs/namei.c:3559
 do_sys_open+0x3fe/0x5d0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1110
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413941
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:00007f8b401147a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000413941
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f8b40114850
RBP: 000000000075bfc8 R08: 000000000000000f R09: 0000000000000000
R10: 00007f8b401159d0 R11: 0000000000000293 R12: 00007f8b401156d4
R13: 00000000004c9086 R14: 00000000004e0548 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..