CVE-2019-15296: Improper Restriction of Operations within the Bounds of a Memory Buffer

An issue was discovered in Freeware Advanced Audio Decoder 2 (FAAD2) 2.8.8. The faad_resetbits function in libfaad/bits.c is affected by a buffer overflow vulnerability. The number of bits to be read is determined by ld->buffer_size - words*4, cast to uint32. If ld->buffer_size - words*4 is negative, a buffer overflow is later performed via getdword_n(&ld->start[words], ld->bytes_left).