Commit message: None
CVE: CVE-2017-11144
CWE: CWE-754
Vulnerability description: In PHP before 5.6.31, 7.x before 7.0.21, and 7.1.x before 7.1.7, the openssl extension PEM sealing code did not check the return value of the OpenSSL sealing function, which could lead to a crash of the PHP interpreter, related to an interpretation conflict for a negative number in ext/openssl/openssl.c, and an OpenSSL documentation omission.

Project: php
File: openssl.c

PHP_FUNCTION(openssl_seal)
{
	zval *pubkeys, *pubkey, *sealdata, *ekeys, *iv = NULL;
	HashTable *pubkeysht;
	EVP_PKEY **pkeys;
	zend_resource ** key_resources;	/* so we know what to cleanup */
	int i, len1, len2, *eksl, nkeys, iv_len;
	unsigned char iv_buf[EVP_MAX_IV_LENGTH + 1], *buf = NULL, **eks;
	char * data;
	size_t data_len;
	char *method =NULL;
	size_t method_len = 0;
	const EVP_CIPHER *cipher;
	EVP_CIPHER_CTX *ctx;

	if (zend_parse_parameters(ZEND_NUM_ARGS(), "sz/z/a/|sz/", &data, &data_len,
				&sealdata, &ekeys, &pubkeys, &method, &method_len, &iv) == FAILURE) {
		return;
	}
	pubkeysht = Z_ARRVAL_P(pubkeys);
	nkeys = pubkeysht ? zend_hash_num_elements(pubkeysht) : 0;
	if (!nkeys) {
		php_error_docref(NULL, E_WARNING, "Fourth argument to openssl_seal() must be a non-empty array");
		RETURN_FALSE;
	}

	PHP_OPENSSL_CHECK_SIZE_T_TO_INT(data_len, data);

	if (method) {
		cipher = EVP_get_cipherbyname(method);
		if (!cipher) {
			php_error_docref(NULL, E_WARNING, "Unknown signature algorithm.");
			RETURN_FALSE;
		}
	} else {
		cipher = EVP_rc4();
	}

	iv_len = EVP_CIPHER_iv_length(cipher);
	if (!iv && iv_len > 0) {
		php_error_docref(NULL, E_WARNING,
				"Cipher algorithm requires an IV to be supplied as a sixth parameter");
		RETURN_FALSE;
	}

	pkeys = safe_emalloc(nkeys, sizeof(*pkeys), 0);
	eksl = safe_emalloc(nkeys, sizeof(*eksl), 0);
	eks = safe_emalloc(nkeys, sizeof(*eks), 0);
	memset(eks, 0, sizeof(*eks) * nkeys);
	key_resources = safe_emalloc(nkeys, sizeof(zend_resource*), 0);
	memset(key_resources, 0, sizeof(zend_resource*) * nkeys);
	memset(pkeys, 0, sizeof(*pkeys) * nkeys);

	/* get the public keys we are using to seal this data */
	i = 0;
	ZEND_HASH_FOREACH_VAL(pubkeysht, pubkey) {
		pkeys[i] = php_openssl_evp_from_zval(pubkey, 1, NULL, 0, 0, &key_resources[i]);
		if (pkeys[i] == NULL) {
			php_error_docref(NULL, E_WARNING, "not a public key (%dth member of pubkeys)", i+1);
			RETVAL_FALSE;
			goto clean_exit;
		}
		eks[i] = emalloc(EVP_PKEY_size(pkeys[i]) + 1);
		i++;
	} ZEND_HASH_FOREACH_END();

	ctx = EVP_CIPHER_CTX_new();
	if (ctx == NULL || !EVP_EncryptInit(ctx,cipher,NULL,NULL)) {
		EVP_CIPHER_CTX_free(ctx);
		php_openssl_store_errors();
		RETVAL_FALSE;
		goto clean_exit;
	}

	/* allocate one byte extra to make room for \0 */
        buf = emalloc(data_len + EVP_CIPHER_CTX_block_size(ctx));
        EVP_CIPHER_CTX_cleanup(ctx);
 
       if (EVP_SealInit(ctx, cipher, eks, eksl, &iv_buf[0], pkeys, nkeys) <= 0 ||
                        !EVP_SealUpdate(ctx, buf, &len1, (unsigned char *)data, (int)data_len) ||
                        !EVP_SealFinal(ctx, buf + len1, &len2)) {
                efree(buf);
		EVP_CIPHER_CTX_free(ctx);
		php_openssl_store_errors();
		RETVAL_FALSE;
		goto clean_exit;
	}

	if (len1 + len2 > 0) {
		zval_dtor(sealdata);
		ZVAL_NEW_STR(sealdata, zend_string_init((char*)buf, len1 + len2, 0));
		efree(buf);

		zval_dtor(ekeys);
		array_init(ekeys);
		for (i=0; i<nkeys; i++) {
			eks[i][eksl[i]] = '\0';
			add_next_index_stringl(ekeys, (const char*)eks[i], eksl[i]);
			efree(eks[i]);
			eks[i] = NULL;
		}

		if (iv) {
			zval_dtor(iv);
			iv_buf[iv_len] = '\0';
			ZVAL_NEW_STR(iv, zend_string_init((char*)iv_buf, iv_len, 0));
		}
	} else {
		efree(buf);
	}
	RETVAL_LONG(len1 + len2);
	EVP_CIPHER_CTX_free(ctx);

clean_exit:
	for (i=0; i<nkeys; i++) {
		if (key_resources[i] == NULL && pkeys[i] != NULL) {
			EVP_PKEY_free(pkeys[i]);
		}
		if (eks[i]) {
			efree(eks[i]);
		}
	}
	efree(eks);
	efree(eksl);
	efree(pkeys);
	efree(key_resources);
}