Heap-memory write in FFMPEG

A heap out-of-bounds memory write exists in FFMPEG since version 5.1. The size calculation in build_open_gop_key_points() goes through all entries in the loop and adds sc->ctts_data[i].count to sc->sample_offsets_count. This can lead to an integer overflow resulting in a small allocation with av_calloc(). An attacker can cause remote code execution via a malicious mp4 file. We recommend upgrading past commit c953baa084607dd1d84c3bfcce3cf6a87c3e6e05