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;
	HashTable *pubkeysht;
	HashPosition pos;
	EVP_PKEY **pkeys;
	long * key_resources;	/* so we know what to cleanup */
	int i, len1, len2, *eksl, nkeys;
	unsigned char *buf = NULL, **eks;
	char * data; int data_len;
	char *method =NULL;
	int method_len = 0;
	const EVP_CIPHER *cipher;
	EVP_CIPHER_CTX ctx;

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

	if (method) {
		cipher = EVP_get_cipherbyname(method);
		if (!cipher) {
			php_error_docref(NULL TSRMLS_CC, E_WARNING, "Unknown signature algorithm.");
			RETURN_FALSE;
		}
		if (EVP_CIPHER_iv_length(cipher) > 0) {
			php_error_docref(NULL TSRMLS_CC, E_WARNING, "Ciphers with modes requiring IV are not supported");
			RETURN_FALSE;
		}
	} else {
		cipher = EVP_rc4();
	}

	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(long), 0);
	memset(key_resources, 0, sizeof(*key_resources) * nkeys);

	/* get the public keys we are using to seal this data */
	zend_hash_internal_pointer_reset_ex(pubkeysht, &pos);
	i = 0;
	while (zend_hash_get_current_data_ex(pubkeysht, (void **) &pubkey,
				&pos) == SUCCESS) {
		pkeys[i] = php_openssl_evp_from_zval(pubkey, 1, NULL, 0, &key_resources[i] TSRMLS_CC);
		if (pkeys[i] == NULL) {
			php_error_docref(NULL TSRMLS_CC, 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);
		zend_hash_move_forward_ex(pubkeysht, &pos);
		i++;
	}

	if (!EVP_EncryptInit(&ctx,cipher,NULL,NULL)) {
		RETVAL_FALSE;
		EVP_CIPHER_CTX_cleanup(&ctx);
		goto clean_exit;
	}

#if 0
	/* Need this if allow ciphers that require initialization vector */
	ivlen = EVP_CIPHER_CTX_iv_length(&ctx);
	iv = ivlen ? emalloc(ivlen + 1) : NULL;
#endif
	/* 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, NULL, pkeys, nkeys) || !EVP_SealUpdate(&ctx, buf, &len1, (unsigned char *)data, data_len)) {
                RETVAL_FALSE;
                efree(buf);
                EVP_CIPHER_CTX_cleanup(&ctx);
                goto clean_exit;
        }
 
       EVP_SealFinal(&ctx, buf + len1, &len2);
        if (len1 + len2 > 0) {
                zval_dtor(sealdata);
                buf[len1 + len2] = '\0';
		buf = erealloc(buf, len1 + len2 + 1);
		ZVAL_STRINGL(sealdata, (char *)buf, len1 + len2, 0);

		zval_dtor(ekeys);
		array_init(ekeys);
		for (i=0; i<nkeys; i++) {
			eks[i][eksl[i]] = '\0';
			add_next_index_stringl(ekeys, erealloc(eks[i], eksl[i] + 1), eksl[i], 0);
			eks[i] = NULL;
		}
#if 0
		/* If allow ciphers that need IV, we need this */
		zval_dtor(*ivec);
		if (ivlen) {
			iv[ivlen] = '\0';
			ZVAL_STRINGL(*ivec, erealloc(iv, ivlen + 1), ivlen, 0);
		} else {
			ZVAL_EMPTY_STRING(*ivec);
		}
#endif
	} else {
		efree(buf);
	}
	RETVAL_LONG(len1 + len2);
	EVP_CIPHER_CTX_cleanup(&ctx);

clean_exit:
	for (i=0; i<nkeys; i++) {
		if (key_resources[i] == -1) {
			EVP_PKEY_free(pkeys[i]);
		}
		if (eks[i]) { 
			efree(eks[i]);
		}
	}
	efree(eks);
	efree(eksl);
	efree(pkeys);
	efree(key_resources);
}