commit f0fd4c3aee3622cff5911f7fbf546e8d2a89b810
author Gilles Peskine <Gilles.Peskine@arm.com> Mon Dec 13 12:36:15 2021 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Mon Dec 13 12:36:15 2021 +0100
tree f7218065d2911cb1d8183859d61ae13ce7162fbb
parent c2f7b75a71e6d8da7c2204e2a053acf1d095521a

mbedtls_ssl_parse_finished: zeroize expected finished value on error

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index a974dbb..4a1191a 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2884,7 +2884,7 @@
     if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
-        return( ret );
+        goto exit;
     }
 
     if( ssl->in_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE )
@@ -2892,7 +2892,8 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
         mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                                         MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
-        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+        ret = MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
+        goto exit;
     }
 
     hash_len = 12;
@@ -2901,7 +2902,8 @@
     {
         mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                                         MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
-        return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
+        ret = MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
+        goto exit;
     }
 
     if( ssl->in_hslen  != mbedtls_ssl_hs_hdr_len( ssl ) + hash_len )
@@ -2909,7 +2911,8 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
         mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                                         MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
-        return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+        ret = MBEDTLS_ERR_SSL_DECODE_ERROR;
+        goto exit;
     }
 
     if( mbedtls_ct_memcmp( ssl->in_msg + mbedtls_ssl_hs_hdr_len( ssl ),
@@ -2918,7 +2921,8 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad finished message" ) );
         mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
                                         MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR );
-        return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+        ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
+        goto exit;
     }
 
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
@@ -2947,7 +2951,9 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse finished" ) );
 
-    return( 0 );
+exit:
+    mbedtls_platform_zeroize( buf, hash_len );
+    return( ret );
 }
 
 static void ssl_handshake_params_init( mbedtls_ssl_handshake_params *handshake )