------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 5956 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 5956 Comm: syz-executor.4 Not tainted 5.5.0-rc2-syzkaller #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+0xef/0x16e lib/dump_stack.c:118
 panic+0x2aa/0x6e1 kernel/panic.c:221
 __warn.cold+0x2f/0x30 kernel/panic.c:582
 report_bug+0x27b/0x2f0 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+0x12b/0x1e0 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Code: 05 31 ff 89 de e8 27 5d 59 ff 84 db 0f 85 36 ff ff ff e8 ea 5b 59 ff 48 c7 c7 60 b8 da 85 c6 05 ab 8c c0 05 01 e8 9f 78 2e ff <0f> 0b e9 17 ff ff ff e8 cb 5b 59 ff 0f b6 1d 90 8c c0 05 31 ff 89
RSP: 0018:ffff8881aea9f950 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 00000000000063b0 RSI: ffffffff81295dad RDI: ffffed1035d53f1c
RBP: 0000000000000002 R08: ffff8881cfc34980 R09: fffffbfff11f1eb8
R10: fffffbfff11f1eb7 R11: ffffffff88f8f5bf R12: ffff8881ac5c4620
R13: 0000000000000000 R14: ffff8881d0b6d3e0 R15: ffff8881ca99997c
 refcount_add include/linux/refcount.h:191 [inline]
 refcount_inc include/linux/refcount.h:228 [inline]
 kref_get include/linux/kref.h:45 [inline]
 kobject_get+0x12b/0x150 lib/kobject.c:644
 cdev_get+0x5c/0xb0 fs/char_dev.c:355
 chrdev_open+0xaa/0x5c0 fs/char_dev.c:400
 do_dentry_open+0x494/0x1120 fs/open.c:797
 do_last fs/namei.c:3420 [inline]
 path_openat+0x13f4/0x3e70 fs/namei.c:3537
 do_filp_open+0x1a1/0x280 fs/namei.c:3567
 do_sys_open+0x3c0/0x580 fs/open.c:1097
 do_syscall_64+0xb6/0x5c0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4146b1
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:00007f3348a1c7a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 00000000004146b1
RDX: 0000000000000000 RSI: 0000000000080041 RDI: 00007f3348a1c850
RBP: 000000000075bfc8 R08: 00007f3348a1c7b0 R09: 000000000075bfc8
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f3348a1d6d4
R13: 00000000004cafa4 R14: 00000000004e4648 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..