In the Linux kernel 4.14.x, 4.15.x, 4.16.x, 4.17.x, and 4.18.x before 4.18.13, faulty computation of numeric bounds in the BPF verifier permits out-of-bounds memory accesses because adjust_scalar_min_max_vals in kernel/bpf/verifier.c mishandles 32-bit right shifts.
https://usn.ubuntu.com/3847-3/
https://usn.ubuntu.com/3847-2/
https://usn.ubuntu.com/3847-1/
https://usn.ubuntu.com/3835-1/
https://usn.ubuntu.com/3832-1/
https://support.f5.com/csp/article/K38456756
https://github.com/torvalds/linux/commit/b799207e1e1816b09e7a5920fbb2d5fcf6edd681
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.13
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.75
https://bugs.chromium.org/p/project-zero/issues/detail?id=1686
https://access.redhat.com/errata/RHSA-2019:0514