------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 10275 at lib/refcount.c:25 refcount_warn_saturate+0x174/0x1f0 lib/refcount.c:25 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 10275 Comm: syz-executor.5 Not tainted 5.4.0-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+0x197/0x210 lib/dump_stack.c:118 panic+0x2e3/0x75c kernel/panic.c:221 __warn.cold+0x2f/0x3e 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:1027 RIP: 0010:refcount_warn_saturate+0x174/0x1f0 lib/refcount.c:25 Code: 06 31 ff 89 de e8 bc 38 e8 fd 84 db 0f 85 33 ff ff ff e8 6f 37 e8 fd 48 c7 c7 00 53 4f 88 c6 05 e6 b6 a5 06 01 e8 db eb b8 fd <0f> 0b e9 14 ff ff ff e8 50 37 e8 fd 0f b6 1d cb b6 a5 06 31 ff 89 RSP: 0018:ffff88807ffff8a8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815e4316 RDI: ffffed100fffff07 RBP: ffff88807ffff8b8 R08: ffff8880818882c0 R09: fffffbfff15d29a9 R10: fffffbfff15d29a8 R11: ffffffff8ae94d47 R12: 0000000000000002 R13: ffff88808d751660 R14: ffff888090d282c0 R15: ffff8880a3417498 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+0x134/0x150 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+0x4e6/0x1380 fs/open.c:797 vfs_open+0xa0/0xd0 fs/open.c:914 do_last fs/namei.c:3408 [inline] path_openat+0x10e4/0x46d0 fs/namei.c:3525 do_filp_open+0x1a1/0x280 fs/namei.c:3555 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/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4143f0 Code: 05 48 3d 01 f0 ff ff 0f 83 2d 19 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 83 3d 7d 40 66 00 00 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 RSP: 002b:00007ffc897c3228 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 00000000004143f0 RDX: 0000000000000000 RSI: 0100000000000000 RDI: 00007ffc897c32d0 RBP: 000000000075bf20 R08: 000000000000000f R09: 0000000000000000 R10: 0000000000760098 R11: 0000000000000246 R12: 000000000133d914 R13: 00000000004ca395 R14: 00000000004e2a10 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..