kernel/bpf/verifier.c in the Linux kernel 4.9.x through 4.9.71 does not check the relationship between pointer values and the BPF stack, which allows local users to cause a denial of service (integer overflow or invalid memory access) or possibly have unspecified other impact.
https://www.spinics.net/lists/stable/msg206985.html
https://www.debian.org/security/2017/dsa-4073
https://usn.ubuntu.com/usn/usn-3523-2/
https://usn.ubuntu.com/3523-3/