kernel/bpf/verifier.c in the Linux kernel through 4.14.8 allows local users to cause a denial of service (memory corruption) or possibly have unspecified other impact by leveraging register truncation mishandling.
https://github.com/torvalds/linux/commit/0c17d1d2c61936401f4702e1846e2c19b200f958
https://bugs.chromium.org/p/project-zero/issues/detail?id=1454
http://www.securityfocus.com/bid/102267