commit 6220ecbc485ffb935225bab298d7f707c33bacfa
author Andres AG <andres.amayagarcia@arm.com> Mon Sep 26 14:53:05 2016 +0100
committer Simon Butcher <simon.butcher@arm.com> Thu Oct 13 15:43:46 2016 +0100
tree 81fe43ed79a52d172e9a10fc3eb5733bef42c478
parent 8390e0a97c18da6284f2888b61ddca6cac5ac192

Fix overread when verifying SERVER_HELLO in DTLS

library/ssl_cli.c

diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 16fd43b..3d7283c 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1226,6 +1226,15 @@
     cookie_len = *p++;
     MBEDTLS_SSL_DEBUG_BUF( 3, "cookie", p, cookie_len );
 
+    if( ( ssl->in_msg + ssl->in_msglen ) - p < cookie_len )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1,
+            ( "cookie length does not match incoming message size" ) );
+        mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                                    MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
     mbedtls_free( ssl->handshake->verify_cookie );
 
     ssl->handshake->verify_cookie = mbedtls_calloc( 1, cookie_len );