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.
git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0c17d1d2c61936401f4702e1846e2c19b200f958
openwall.com/lists/oss-security/2017/12/21/2
www.securityfocus.com/bid/102267
bugs.chromium.org/p/project-zero/issues/detail?id=1454
github.com/torvalds/linux/commit/0c17d1d2c61936401f4702e1846e2c19b200f958