Improve handling of legacy_compression_methods in ssl_tls13_parse_client_hello()
Signed-off-by: Waleed Elmelegy <waleed.elmelegy@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index ca3ea53..ae690e5 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1265,8 +1265,6 @@
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
int hrr_required = 0;
int no_usable_share_for_key_agreement = 0;
- unsigned char legacy_compression_methods_len;
- unsigned char legacy_compression_methods;
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED)
int got_psk = 0;
@@ -1364,19 +1362,17 @@
p += cipher_suites_len;
cipher_suites_end = p;
- legacy_compression_methods_len = *p;
- legacy_compression_methods = *(p+1);
-
- if (legacy_compression_methods_len != 1 || legacy_compression_methods != 0) {
- return SSL_CLIENT_HELLO_TLS1_2;
- }
+ /* Check if we have enough data to for legacy_compression_methods
+ * and a length byte.
+ */
+ MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 1 + p[0]);
/*
* Search for the supported versions extension and parse it to determine
* if the client supports TLS 1.3.
*/
ret = mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts(
- ssl, p + 2, end,
+ ssl, p + 1 + p[0], end,
&supported_versions_data, &supported_versions_data_end);
if (ret < 0) {
MBEDTLS_SSL_DEBUG_RET(1,