Add error checking to PKCS1_MGF1. From HEAD.

	EVP_MD_CTX c;

	unsigned char md[EVP_MAX_MD_SIZE];

	int mdlen;

	int rv = -1;

	EVP_MD_CTX_init(&c);

	mdlen = EVP_MD_size(dgst);

	if (mdlen < 0)

		return -1;

		goto err;

	for (i = 0; outlen < len; i++)

		{

		cnt[0] = (unsigned char)((i >> 24) & 255);

		cnt[1] = (unsigned char)((i >> 16) & 255);

		cnt[2] = (unsigned char)((i >> 8)) & 255;

		cnt[3] = (unsigned char)(i & 255);

		EVP_DigestInit_ex(&c,dgst, NULL);

		EVP_DigestUpdate(&c, seed, seedlen);

		EVP_DigestUpdate(&c, cnt, 4);

		if (!EVP_DigestInit_ex(&c,dgst, NULL)

			|| !EVP_DigestUpdate(&c, seed, seedlen)

			|| !EVP_DigestUpdate(&c, cnt, 4))

			goto err;

		if (outlen + mdlen <= len)

			{

			EVP_DigestFinal_ex(&c, mask + outlen, NULL);

			if (!EVP_DigestFinal_ex(&c, mask + outlen, NULL))

				goto err;

			outlen += mdlen;

			}

		else

			{

			EVP_DigestFinal_ex(&c, md, NULL);

			if (!EVP_DigestFinal_ex(&c, md, NULL))

				goto err;

			memcpy(mask + outlen, md, len - outlen);

			outlen = len;

			}

		}

	rv = 0;

	err:

	EVP_MD_CTX_cleanup(&c);

	return 0;

	return rv;

	}

static int MGF1(unsigned char *mask, long len, const unsigned char *seed,