NULL Pointer Dereference

Summary

Remote packet capture support is disabled by default in libpcap. When a user builds libpcap with remote packet capture support enabled, one of the functions that become available is "pcap_findalldevs_ex()". One of the function arguments can be a filesystem path, which normally means a directory with input data files. When the specified path cannot be used as a directory, the function receives NULL from "opendir()" but does not check the return value and passes the NULL value to "readdir()", which causes a NULL pointer to dereference. This issue affects libpcap versions prior to 1.10.5.