GHSL-2024-228: GStreamer has an out-of-bounds write in SSA subtitle parser

GStreamer is a library for constructing graphs of media-handling components. An OOB-write vulnerability has been identified in the gst_ssa_parse_remove_override_codes function of the gstssaparse.c file. This function is responsible for parsing and removing SSA (SubStation Alpha) style override codes, which are enclosed in curly brackets ({}). The issue arises when a closing curly bracket "}" appears before an opening curly bracket "{" in the input string. In this case, memmove() incorrectly duplicates a substring. With each successive loop iteration, the size passed to memmove() becomes progressively larger (strlen(end+1)), leading to a write beyond the allocated memory bounds. This vulnerability is fixed in 1.24.10.