OSV-2020-1188 Heap-buffer-overflow in pcpp::IPv6Extension::getExtensionLen

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=22105 Crash type: Heap-buffer-overflow READ 1 Crash state: pcpp::IPv6Extension::getExtensionLen pcpp::IPv6Layer::parseExtensions pcpp::IPv6Layer::IPv6Layer...