CVE-2019-20429

In the Lustre file system before 2.12.3, the ptlrpc module has an out-of-bounds read and panic (via a modified lm_bufcount field) due to the lack of validation for specific fields of packets sent by a client. This is caused by interaction between sptlrpc_svc_unwrap_request and lustre_msg_hdr_size_v2.