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.
www.securityfocus.com/bid/102321
www.securitytracker.com/id/1040058
anonscm.debian.org/cgit/kernel/linux.git/tree/debian/patches/bugfix/all/bpf-reject-out-of-bounds-stack-pointer-calculation.patch?h=stretch-security
usn.ubuntu.com/3523-3/
usn.ubuntu.com/usn/usn-3523-2/
www.debian.org/security/2017/dsa-4073
www.spinics.net/lists/stable/msg206985.html