mbedtls: make ciphers_list a static array

Instead of allocating the ciphers_list, make it a static array.  This
prevents us from leaking it or having to manage its memory.

src/streams/mbedtls.c

@@ -43,12 +43,13 @@
 
 #undef inline
 
-mbedtls_ssl_config *git__ssl_conf;
-mbedtls_entropy_context *mbedtls_entropy;
-
 #define GIT_SSL_DEFAULT_CIPHERS "TLS-ECDHE-ECDSA-WITH-AES-128-GCM-SHA256:TLS-ECDHE-RSA-WITH-AES-128-GCM-SHA256:TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384:TLS-ECDHE-RSA-WITH-AES-256-GCM-SHA384:TLS-DHE-RSA-WITH-AES-128-GCM-SHA256:TLS-DHE-DSS-WITH-AES-128-GCM-SHA256:TLS-DHE-RSA-WITH-AES-256-GCM-SHA384:TLS-DHE-DSS-WITH-AES-256-GCM-SHA384:TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA256:TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA256:TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA:TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA:TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA384:TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA384:TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA:TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA:TLS-DHE-RSA-WITH-AES-128-CBC-SHA256:TLS-DHE-RSA-WITH-AES-256-CBC-SHA256:TLS-DHE-RSA-WITH-AES-128-CBC-SHA:TLS-DHE-RSA-WITH-AES-256-CBC-SHA:TLS-DHE-DSS-WITH-AES-128-CBC-SHA256:TLS-DHE-DSS-WITH-AES-256-CBC-SHA256:TLS-DHE-DSS-WITH-AES-128-CBC-SHA:TLS-DHE-DSS-WITH-AES-256-CBC-SHA:TLS-RSA-WITH-AES-128-GCM-SHA256:TLS-RSA-WITH-AES-256-GCM-SHA384:TLS-RSA-WITH-AES-128-CBC-SHA256:TLS-RSA-WITH-AES-256-CBC-SHA256:TLS-RSA-WITH-AES-128-CBC-SHA:TLS-RSA-WITH-AES-256-CBC-SHA"
 #define GIT_SSL_DEFAULT_CIPHERS_COUNT 30
 
+mbedtls_ssl_config *git__ssl_conf;
+static int ciphers_list[GIT_SSL_DEFAULT_CIPHERS_COUNT];
+mbedtls_entropy_context *mbedtls_entropy;
+
 /**
  * This function aims to clean-up the SSL context which
  * we allocated.
@@ -80,8 +81,7 @@ int git_mbedtls_stream_global_init(void)
 	struct stat statbuf;
 	mbedtls_ctr_drbg_context *ctr_drbg = NULL;
 
-	int *ciphers_list = NULL;
-	int ciphers_known = 0;
+	size_t ciphers_known = 0;
 	char *cipher_name = NULL;
 	char *cipher_string = NULL;
 	char *cipher_string_tmp = NULL;
@@ -109,9 +109,6 @@ int git_mbedtls_stream_global_init(void)
 	mbedtls_ssl_conf_authmode(git__ssl_conf, MBEDTLS_SSL_VERIFY_OPTIONAL);
 
 	/* set the list of allowed ciphersuites */
-	ciphers_list = git__calloc(GIT_SSL_DEFAULT_CIPHERS_COUNT, sizeof(int));
-	GITERR_CHECK_ALLOC(ciphers_list);
-
 	ciphers_known = 0;
 	cipher_string = cipher_string_tmp = git__strdup(GIT_SSL_DEFAULT_CIPHERS);
 	GITERR_CHECK_ALLOC(cipher_string);
@@ -120,6 +117,11 @@ int git_mbedtls_stream_global_init(void)
 		int cipherid = mbedtls_ssl_get_ciphersuite_id(cipher_name);
 		if (cipherid == 0) continue;
 
+		if (ciphers_known >= ARRAY_SIZE(ciphers_list)) {
+			giterr_set(GITERR_SSL, "out of cipher list space");
+			goto cleanup;
+		}
+
 		ciphers_list[ciphers_known++] = cipherid;
 	}
 	git__free(cipher_string);
@@ -129,7 +131,6 @@ int git_mbedtls_stream_global_init(void)
 		goto cleanup;
 	}
 	mbedtls_ssl_conf_ciphersuites(git__ssl_conf, ciphers_list);
-	git__free(ciphers_list);
 
 	/* Seeding the random number generator */
 	mbedtls_entropy = git__malloc(sizeof(mbedtls_entropy_context));
@@ -167,7 +168,6 @@ cleanup:
 	mbedtls_ctr_drbg_free(ctr_drbg);
 	git__free(ctr_drbg);
 	mbedtls_ssl_config_free(git__ssl_conf);
-	git__free(ciphers_list);
 	git__free(git__ssl_conf);
 	git__ssl_conf = NULL;