static int openssl_x509v3_subjectAltName(BIO *bio, X509_EXTENSION *extension)
{
	GENERAL_NAMES *names;
	const X509V3_EXT_METHOD *method = NULL;
	long i, length, num;
	const unsigned char *p;

	method = X509V3_EXT_get(extension);
	if (method == NULL) {
		return -1;
	}

	p = extension->value->data;
	length = extension->value->length;
	if (method->it) {
		names = (GENERAL_NAMES*)(ASN1_item_d2i(NULL, &p, length,
						       ASN1_ITEM_ptr(method->it)));
	} else {
		names = (GENERAL_NAMES*)(method->d2i(NULL, &p, length));
	}
	if (names == NULL) {
		return -1;
	}

	num = sk_GENERAL_NAME_num(names);
	for (i = 0; i < num; i++) {
			GENERAL_NAME *name;
			ASN1_STRING *as;
			name = sk_GENERAL_NAME_value(names, i);
			switch (name->type) {
				case GEN_EMAIL:
					BIO_puts(bio, "email:");
					as = name->d.rfc822Name;
					BIO_write(bio, ASN1_STRING_data(as),
						  ASN1_STRING_length(as));
					break;
				case GEN_DNS:
					BIO_puts(bio, "DNS:");
					as = name->d.dNSName;
					BIO_write(bio, ASN1_STRING_data(as),
						  ASN1_STRING_length(as));
					break;
				case GEN_URI:
					BIO_puts(bio, "URI:");
					as = name->d.uniformResourceIdentifier;
					BIO_write(bio, ASN1_STRING_data(as),
						  ASN1_STRING_length(as));
					break;
				default:
					/* use builtin print for GEN_OTHERNAME, GEN_X400,
					 * GEN_EDIPARTY, GEN_DIRNAME, GEN_IPADD and GEN_RID
					 */
					GENERAL_NAME_print(bio, name);
			}
			/* trailing ', ' except for last element */
			if (i < (num - 1)) {
				BIO_puts(bio, ", ");
			}
	}
	sk_GENERAL_NAME_pop_free(names, GENERAL_NAME_free);

	return 0;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.