------------[ cut here ]------------ refcount_t: increment on 0; use-after-free. WARNING: CPU: 1 PID: 23066 at lib/refcount.c:156 refcount_inc_checked lib/refcount.c:156 [inline] WARNING: CPU: 1 PID: 23066 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: 23066 Comm: syz-executor.0 Not tainted 5.4.0-rc8 #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/0x35 kernel/panic.c:582 report_bug+0x289/0x300 lib/bug.c:195 fixup_bug arch/x86/kernel/traps.c:179 [inline] fixup_bug arch/x86/kernel/traps.c:174 [inline] do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291 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 00 d5 7d 06 31 ff 89 de e8 0b 96 2e fe 84 db 75 dd e8 c2 94 2e fe 48 c7 c7 00 ba e6 87 c6 05 e0 d4 7d 06 01 e8 d7 c7 ff fd <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 RSP: 0018:ffff88805a1878b0 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000019bcd RSI: ffffffff815cf766 RDI: ffffed100b430f08 RBP: ffff88805a1878c0 R08: ffff888099a3c080 R09: fffffbfff14f0140 R10: fffffbfff14f013f R11: ffffffff8a7809ff R12: ffff8880a97da640 R13: 0000000000000000 R14: ffff888097931280 R15: ffff8880a0c43498 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+0x4e6/0x1380 fs/open.c:797 vfs_open+0xa0/0xd0 fs/open.c:914 do_last fs/namei.c:3408 [inline] path_openat+0x10e9/0x46d0 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/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4143d1 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:00007ff30c9b57a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 00000000004143d1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007ff30c9b5850 RBP: 000000000075bfc8 R08: 000000000000000f R09: 0000000000000000 R10: 00007ff30c9b69d0 R11: 0000000000000293 R12: 00007ff30c9b66d4 R13: 00000000004ca143 R14: 00000000004e1eb0 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..