From e699270908f409ecc303bc0c1bb8e3b2675362d7 Mon Sep 17 00:00:00 2001
From: Ron Eldor <Ron.Eldor@arm.com>
Date: Tue, 7 May 2019 18:27:13 +0300
Subject: [PATCH] Add a single exit point in key derivation function

Add a single exit point in `mbedtls_ssl_derive_keys()`.
---
 library/ssl_tls.c | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index da42ed7ae..c2903605c 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1036,7 +1036,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
             ( ret = mbedtls_md_setup( &transform->md_ctx_dec, md_info, 1 ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_setup", ret );
-            return( ret );
+            goto end;
         }
 
         /* Get MAC length */
@@ -1106,7 +1106,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
 #endif
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
-                return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+                ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
+                goto end;
             }
         }
     }
@@ -1168,7 +1169,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
 #endif /* MBEDTLS_SSL_SRV_C */
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
+        goto end;
     }
 
 #if defined(MBEDTLS_SSL_SOME_MODES_USE_MAC)
@@ -1178,7 +1180,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
         if( mac_key_len > sizeof( transform->mac_enc ) )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
-            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+            ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
+            goto end;
         }
 
         memcpy( transform->mac_enc, mac_enc, mac_key_len );
@@ -1202,7 +1205,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
 #endif
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
+        goto end;
     }
 #endif /* MBEDTLS_SSL_SOME_MODES_USE_MAC */
 
@@ -1220,7 +1224,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
                                         mac_key_len ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_hw_record_init", ret );
-            return( MBEDTLS_ERR_SSL_HW_ACCEL_FAILED );
+            ret = MBEDTLS_ERR_SSL_HW_ACCEL_FAILED;
+            goto end;
         }
     }
 #else
@@ -1253,7 +1258,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
         if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup_psa", ret );
-            return( ret );
+            goto end;
         }
 
         if( ret == 0 )
@@ -1279,7 +1284,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
                                  cipher_info ) ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
-        return( ret );
+        goto end;
     }
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
@@ -1296,7 +1301,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
         if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup_psa", ret );
-            return( ret );
+            goto end;
         }
 
         if( ret == 0 )
@@ -1322,7 +1327,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
                                  cipher_info ) ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
-        return( ret );
+        goto end;
     }
 
     if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_enc, key1,
@@ -1330,7 +1335,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
                                MBEDTLS_ENCRYPT ) ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
-        return( ret );
+        goto end;
     }
 
     if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_dec, key2,
@@ -1338,7 +1343,7 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
                                MBEDTLS_DECRYPT ) ) != 0 )
     {
         MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
-        return( ret );
+        goto end;
     }
 
 #if defined(MBEDTLS_CIPHER_MODE_CBC)
@@ -1348,14 +1353,14 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
                                              MBEDTLS_PADDING_NONE ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_set_padding_mode", ret );
-            return( ret );
+            goto end;
         }
 
         if( ( ret = mbedtls_cipher_set_padding_mode( &transform->cipher_ctx_dec,
                                              MBEDTLS_PADDING_NONE ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_set_padding_mode", ret );
-            return( ret );
+            goto end;
         }
     }
 #endif /* MBEDTLS_CIPHER_MODE_CBC */
@@ -1375,7 +1380,8 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
             {
                 MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
                                     MBEDTLS_SSL_COMPRESS_BUFFER_LEN ) );
-                return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
+                ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
+                goto end;
             }
         }
 
@@ -1389,14 +1395,16 @@ int mbedtls_ssl_derive_keys( mbedtls_ssl_context *ssl )
             inflateInit( &transform->ctx_inflate ) != Z_OK )
         {
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "Failed to initialize compression" ) );
-            return( MBEDTLS_ERR_SSL_COMPRESSION_FAILED );
+            ret = MBEDTLS_ERR_SSL_COMPRESSION_FAILED;
+            goto end;
         }
     }
 #endif /* MBEDTLS_ZLIB_SUPPORT */
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= derive keys" ) );
+end:
 
-    return( 0 );
+    return( ret );
 }
 
 #if defined(MBEDTLS_SSL_PROTO_SSL3)