Red Hat DPDK GSO: out-of-bounds read

A flaw was found in the DPDK GSO library. When software GSO copies packet headers into a new mbuf, it does not check that the header fits in the source first segment or in the destination buffer, and a header longer than the configured GSO segment size can underflow the payload-size calculation. A remote or guest-supplied packet processed with software GSO can trigger an out-of-bounds read or write.