Tnef: heap out-of-bounds read in get_rtf_data_from_buf() via uncompressed rtf mapi value

A flaw was found in tnef. An attacker can exploit this vulnerability by providing a specially crafted file containing uncompressed Rich Text Format (RTF) data. Because the application fails to properly validate input buffer boundaries before copying data in get_rtf_data_from_buf(), reading beyond the allocated memory occurs. This flaw can cause the application to crash, leading to a Denial of Service (DoS), or leak sensitive memory contents into extracted output files.