------------[ cut here ]------------
refcount_t: increment on 0; use-after-free.
WARNING: CPU: 0 PID: 28895 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: 28895 Comm: syz-executor.4 Not tainted 5.3.0-rc3+ #65
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+0x1d8/0x2f8 lib/dump_stack.c:113
 panic+0x25c/0x799 kernel/panic.c:219
 __warn+0x22f/0x230 kernel/panic.c:576
 report_bug+0x190/0x290 lib/bug.c:186
 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:1026
RIP: 0010:refcount_inc_checked+0x4b/0x50 lib/refcount.c:156
Code: 3d 3e 93 68 05 01 75 08 e8 b2 61 21 fe 5b 5d c3 e8 aa 61 21 fe c6 05 28 93 68 05 01 48 c7 c7 74 44 45 88 31 c0 e8 75 42 f4 fd <0f> 0b eb df 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 ec 10
RSP: 0018:ffff8880576af9b0 EFLAGS: 00010246
RAX: 1c42d9223358c100 RBX: ffff888094aa1180 RCX: 0000000000040000
RDX: ffffc9000e9a2000 RSI: 000000000001130b RDI: 000000000001130c
RBP: ffff8880576af9b8 R08: ffffffff815cfa34 R09: fffffbfff111a93f
R10: fffffbfff111a93f R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888094aa1148 R14: ffff888094aa1184 R15: ffff888094aa1148
 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+0x73b/0xf90 fs/open.c:797
 vfs_open+0x73/0x80 fs/open.c:906
 do_last fs/namei.c:3416 [inline]
 path_openat+0x1397/0x4460 fs/namei.c:3533
 do_filp_open+0x192/0x3d0 fs/namei.c:3563
 do_sys_open+0x29f/0x560 fs/open.c:1089
 __do_sys_open fs/open.c:1107 [inline]
 __se_sys_open fs/open.c:1102 [inline]
 __x64_sys_open+0x87/0x90 fs/open.c:1102
 do_syscall_64+0xfe/0x140 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x413711
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:00007f7638c717a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000413711
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f7638c71850
RBP: 000000000075bfc8 R08: 000000000000000f R09: 0000000000000000
R10: 00007f7638c729d0 R11: 0000000000000293 R12: 00007f7638c726d4
R13: 00000000004c8bc7 R14: 00000000004dfa38 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..