------------[ cut here ]------------ refcount_t: increment on 0; use-after-free. WARNING: CPU: 0 PID: 7711 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: 7711 Comm: syz-executor.4 Not tainted 5.3.0-rc2+ #55 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+0x29b/0x7d9 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 be ac 93 05 01 75 08 e8 92 d6 10 fe 5b 5d c3 e8 8a d6 10 fe c6 05 a8 ac 93 05 01 48 c7 c7 b9 4b 88 88 31 c0 e8 a5 e7 e1 fd <0f> 0b eb df 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 RSP: 0018:ffff888065d276d8 EFLAGS: 00010246 RAX: 2d495555a7e4d200 RBX: ffff8880612f0f80 RCX: 0000000000040000 RDX: ffffc90005cc5000 RSI: 0000000000011e6f RDI: 0000000000011e70 RBP: ffff888065d276e0 R08: ffffffff816068b4 R09: ffffed1015d46088 R10: ffffed1015d46088 R11: 0000000000000000 R12: dffffc0000000000 R13: ffff8880612f0f48 R14: ffff8880612f0f84 R15: ffff8880612f0f48 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+0x1d1/0x670 fs/char_dev.c:400 do_dentry_open+0x7d1/0x1080 fs/open.c:797 vfs_open+0x73/0x80 fs/open.c:906 do_last fs/namei.c:3416 [inline] path_openat+0x136d/0x4440 fs/namei.c:3533 do_filp_open+0x1f7/0x430 fs/namei.c:3563 do_sys_open+0x343/0x620 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:00007fab0f60a7a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000413711 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fab0f60a850 RBP: 000000000075bf20 R08: 000000000000000f R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00007fab0f60b6d4 R13: 00000000004c8bc7 R14: 00000000004dfa38 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..