Reject out-of-bounds DTLS CID length in ssl_context_load

Signed-off-by: Nadav0077 <[email protected]>

ChangeLog.d/serialized-data-load-hardening.txt

@@ -0,0 +1,5 @@
+Bugfix
+   * Reject malformed TLS 1.3 serialized sessions instead of accepting
+     unterminated strings or extra trailing data.
+   * Reject serialized SSL contexts whose DTLS Connection ID length exceeds
+     the maximum supported size, instead of overflowing the internal buffer.

ChangeLog.d/tls13-session-load-hardening.txt

@@ -1,3 +0,0 @@
-Bugfix
-   * Reject malformed TLS 1.3 serialized sessions instead of accepting
-     unterminated strings or extra trailing data.

library/ssl_tls.c

@@ -5012,6 +5012,10 @@ static int ssl_context_load(mbedtls_ssl_context *ssl,
         return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
     }
 
+    if (ssl->transform->in_cid_len > sizeof(ssl->transform->in_cid)) {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
     memcpy(ssl->transform->in_cid, p, ssl->transform->in_cid_len);
     p += ssl->transform->in_cid_len;
 
@@ -5021,6 +5025,10 @@ static int ssl_context_load(mbedtls_ssl_context *ssl,
         return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
     }
 
+    if (ssl->transform->out_cid_len > sizeof(ssl->transform->out_cid)) {
+        return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
+    }
+
     memcpy(ssl->transform->out_cid, p, ssl->transform->out_cid_len);
     p += ssl->transform->out_cid_len;
 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */