int bmp_validate(jas_stream_t *in)
{
	int n;
	int i;
	jas_uchar buf[2];

	assert(JAS_STREAM_MAXPUTBACK >= 2);

	/* Read the first two characters that constitute the signature. */
	if ((n = jas_stream_read(in, (char *) buf, 2)) < 0) {
		return -1;
	}
	/* Put the characters read back onto the stream. */
	for (i = n - 1; i >= 0; --i) {
		if (jas_stream_ungetc(in, buf[i]) == EOF) {
			return -1;
		}
	}
	/* Did we read enough characters? */
	if (n < 2) {
		return -1;
	}
	/* Is the signature correct for the BMP format? */
	if (buf[0] == (BMP_MAGIC & 0xff) && buf[1] == (BMP_MAGIC >> 8)) {
		return 0;
	}
	return -1;
}
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.