------------[ cut here ]------------ refcount_t: increment on 0; use-after-free. WARNING: CPU: 0 PID: 7893 at lib/refcount.c:156 refcount_inc_checked lib/refcount.c:156 [inline] WARNING: CPU: 0 PID: 7893 at lib/refcount.c:156 refcount_inc_checked+0x61/0x70 lib/refcount.c:154 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 7893 Comm: syz-executor835 Not tainted 5.1.0-rc6-next-20190426 #31 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+0x172/0x1f0 lib/dump_stack.c:113 panic+0x2cb/0x75a kernel/panic.c:218 __warn.cold+0x20/0x47 kernel/panic.c:580 report_bug+0x263/0x2b0 lib/bug.c:186 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+0x14/0x20 arch/x86/entry/entry_64.S:972 RIP: 0010:refcount_inc_checked lib/refcount.c:156 [inline] RIP: 0010:refcount_inc_checked+0x61/0x70 lib/refcount.c:154 Code: 1d 5c 80 27 06 31 ff 89 de e8 6b 69 3c fe 84 db 75 dd e8 22 68 3c fe 48 c7 c7 40 2a a2 87 c6 05 3c 80 27 06 01 e8 9d 8b 0e fe <0f> 0b eb c1 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 RSP: 0018:ffff8880a4def8b8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff815b4656 RDI: ffffed10149bdf09 RBP: ffff8880a4def8c8 R08: ffff88809f88c280 R09: ffff88809f88cb20 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a430d2b8 R13: 0000000000000000 R14: ffff88808c2a5ac0 R15: ffff8880a9151f10 kref_get include/linux/kref.h:47 [inline] kobject_get+0x66/0xc0 lib/kobject.c:613 cdev_get+0x60/0xb0 fs/char_dev.c:354 chrdev_open+0xb0/0x6b0 fs/char_dev.c:399 do_dentry_open+0x4e2/0x1250 fs/open.c:777 vfs_open+0xa0/0xd0 fs/open.c:886 do_last fs/namei.c:3416 [inline] path_openat+0x10e9/0x46e0 fs/namei.c:3533 do_filp_open+0x1a1/0x280 fs/namei.c:3563 do_sys_open+0x3fe/0x5d0 fs/open.c:1069 __do_sys_open fs/open.c:1087 [inline] __se_sys_open fs/open.c:1082 [inline] __x64_sys_open+0x7e/0xc0 fs/open.c:1082 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x407841 Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 a4 18 00 00 c3 48 83 ec 08 e8 8a fa ff ff 48 89 04 24 b8 02 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 d3 fa ff ff 48 89 d0 48 83 c4 08 48 3d 01 RSP: 002b:00007fa8e6cd78b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 0000000000407841 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fa8e6cd78d0 RBP: 00000000006dec30 R08: 000000000000000f R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 00000000006dec3c R13: 00007fffb0c3dd3f R14: 00007fa8e6cd89c0 R15: 0000000000000003 Kernel Offset: disabled Rebooting in 86400 seconds..