------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 8431 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: 8431 Comm: syz-executor.3 Not tainted 5.5.0-rc3-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 f7 35 59 ff 84 db 0f 85 36 ff ff ff e8 ba 34 59 ff 48 c7 c7 a0 b6 da 85 c6 05 5c 65 9f 05 01 e8 2f 55 2e ff <0f> 0b e9 17 ff ff ff e8 9b 34 59 ff 0f b6 1d 41 65 9f 05 31 ff 89 RSP: 0018:ffff8881cda9f950 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000006612 RSI: ffffffff81295b3d RDI: ffffed1039b53f1c RBP: 0000000000000002 R08: ffff8881cefa3100 R09: fffffbfff11ad8b0 R10: fffffbfff11ad8af R11: ffffffff88d6c57f R12: ffff8881d52c8620 R13: 0000000000000000 R14: ffff8881c19c2d80 R15: ffff8881c716d1fc 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: 0033:0x414ce1 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:00007f78e78557a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000414ce1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f78e7855850 RBP: 000000000075bfc8 R08: 00007f78e78557b0 R09: 000000000075bfc8 R10: 0000000000000000 R11: 0000000000000293 R12: 00007f78e78566d4 R13: 00000000004cbfe3 R14: 00000000004e6c30 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..