Merge remote-tracking branch 'upstream-restricted/pr/472' into mbedtls-2.1-restricted-proposed

Remove trailing whitespace from ChangeLog.
diff --git a/ChangeLog b/ChangeLog
index 6f3fcda..0af942b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,11 @@
      where an optional signature algorithms list is expected in the cases of
      the signature algorithms section being too short. In the debug builds
      the overread data is printed to the standard output.
+   * Fix a client-side bug in the validation of the server's ciphersuite choice
+     potentially leading to the client accepting a ciphersuite it didn't offer
+     or one that cannot be used with the (D)TLS version chosen by the server.
+     This may lead to corruption of internal data structures for some
+     configurations.
 
 Bugfix
    * Add missing dependencies in test suites that led to build failures
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 1899886..2d1dcf8 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -632,6 +632,43 @@
     return( 0 );
 }
 
+/**
+ * \brief           Validate cipher suite against config in SSL context.
+ *
+ * \param suite_info    cipher suite to validate
+ * \param ssl           SSL context
+ * \param min_minor_ver Minimal minor version to accept a cipher suite
+ * \param max_minor_ver Maximal minor version to accept a cipher suite
+ *
+ * \return          0 if valid, else 1
+ */
+static int ssl_validate_ciphersuite( const mbedtls_ssl_ciphersuite_t * suite_info,
+                                     const mbedtls_ssl_context * ssl,
+                                     int min_minor_ver, int max_minor_ver )
+{
+    (void) ssl;
+    if( suite_info == NULL )
+        return( 1 );
+
+    if( suite_info->min_minor_ver > max_minor_ver ||
+            suite_info->max_minor_ver < min_minor_ver )
+        return( 1 );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+            ( suite_info->flags & MBEDTLS_CIPHERSUITE_NODTLS ) )
+        return( 1 );
+#endif
+
+#if defined(MBEDTLS_ARC4_C)
+    if( ssl->conf->arc4_disabled == MBEDTLS_SSL_ARC4_DISABLED &&
+            suite_info->cipher == MBEDTLS_CIPHER_ARC4_128 )
+        return( 1 );
+#endif
+
+    return( 0 );
+}
+
 static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
 {
     int ret;
@@ -784,25 +821,11 @@
     {
         ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuites[i] );
 
-        if( ciphersuite_info == NULL )
+        if( ssl_validate_ciphersuite( ciphersuite_info, ssl,
+                                      ssl->conf->min_minor_ver,
+                                      ssl->conf->max_minor_ver ) != 0 )
             continue;
 
-        if( ciphersuite_info->min_minor_ver > ssl->conf->max_minor_ver ||
-            ciphersuite_info->max_minor_ver < ssl->conf->min_minor_ver )
-            continue;
-
-#if defined(MBEDTLS_SSL_PROTO_DTLS)
-        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
-            ( ciphersuite_info->flags & MBEDTLS_CIPHERSUITE_NODTLS ) )
-            continue;
-#endif
-
-#if defined(MBEDTLS_ARC4_C)
-        if( ssl->conf->arc4_disabled == MBEDTLS_SSL_ARC4_DISABLED &&
-            ciphersuite_info->cipher == MBEDTLS_CIPHER_ARC4_128 )
-            continue;
-#endif
-
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, add ciphersuite: %2d",
                        ciphersuites[i] ) );
 
@@ -1507,18 +1530,9 @@
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %d", i ) );
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, compress alg.: %d", buf[37 + n] ) );
 
-    suite_info = mbedtls_ssl_ciphersuite_from_id( ssl->session_negotiate->ciphersuite );
-    if( suite_info == NULL
-#if defined(MBEDTLS_ARC4_C)
-            || ( ssl->conf->arc4_disabled &&
-                suite_info->cipher == MBEDTLS_CIPHER_ARC4_128 )
-#endif
-        )
-    {
-        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
-        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
-    }
-
+    /*
+     * Perform cipher suite validation in same way as in ssl_write_client_hello.
+     */
     i = 0;
     while( 1 )
     {
@@ -1535,6 +1549,15 @@
         }
     }
 
+    suite_info = mbedtls_ssl_ciphersuite_from_id( ssl->session_negotiate->ciphersuite );
+    if( ssl_validate_ciphersuite( suite_info, ssl, ssl->minor_ver, ssl->minor_ver ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad server hello message" ) );
+        return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
+    }
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %s", suite_info->name ) );
+
     if( comp != MBEDTLS_SSL_COMPRESS_NULL
 #if defined(MBEDTLS_ZLIB_SUPPORT)
         && comp != MBEDTLS_SSL_COMPRESS_DEFLATE