Code injection

In libavformat/nsvdec.c in FFmpeg 2.4 and 3.3.3, a DoS in nsv_parse_NSVf_header() due to lack of an EOF (End of File) check might cause huge CPU consumption. When a crafted NSV file, which claims a large “table_entries_used” field in the header but does not contain sufficient backing data, is provided, the loop over ‘table_entries_used’ would consume huge CPU resources, since there is no EOF check inside the loop.