sound/core/seq_device.c in the Linux kernel before 4.13.4 allows local users to cause a denial of service (snd_rawmidi_dev_seq_free use-after-free and system crash) or possibly have unspecified other impact via a crafted USB device.
https://usn.ubuntu.com/3619-2/
https://usn.ubuntu.com/3619-1/
https://groups.google.com/d/msg/syzkaller/kuZzDHGkQu8/5du20rZEAAAJ
https://github.com/torvalds/linux/commit/fc27fe7e8deef2f37cba3f2be2d52b6ca5eb9d57