Out-of-bounds read in OpenDDS

Summary

OpenDDS is an open source C++ implementation of the Object Management Group (OMG) Data Distribution Service (DDS). Prior to 3.34.0, a network attacker can crash a reachable OpenDDS participant by sending a malformed RTPS UDP submessage whose crafted length or sequence-number state causes dds/DCPS/transport/rtps_udp/RtpsUdpReceiveStrategy.cpp in RtpsUdpReceiveStrategy::handle_input() to advance ACE_Message_Block::rd_ptr() beyond valid data. The parser can then call dds/DCPS/transport/rtps_udp/RtpsSampleHeader.cpp in RtpsSampleHeader::init(), which dereferences the invalid read pointer without first validating it against wr_ptr() or ensuring that a complete submessage header remains. The resulting SIGSEGV occurs in the receive thread, terminates the DDS process, and destroys the DDS entities hosted by that participant. No authentication, prior protocol state, or victim interaction is required. This issue is fixed in version 3.34.0.