[Regression fix] [Data URI parser] Accept data URI with invalid mediatype data

net/base/data_url.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // NOTE: based loosely on mozilla's nsDataChannel.cpp
 
 #include <algorithm>
 
 #include "net/base/data_url.h"
 
@@ skipping 50 matching lines @@
       // The grammar for charset is not specially defined in RFC2045 and
       // RFC2397. It just needs to be a token.
       if (!net::HttpUtil::IsToken(*charset))
         return false;
     }
   }
 
   if (mime_type->empty()) {
     // fallback to defaults if nothing specified in the URL:
     mime_type->assign("text/plain");
-  } else if (!ParseMimeTypeWithoutParameter(*mime_type, NULL, NULL)) {

[asanka, 2014/09/24 00:11:38]

As mentioned elsewhere, it's still a bit worrisome that the mime_type is going
to be returned without any validation which places a heavy burden on callers to
do the validation themselves. E.g. someone stuffing the mime type into a set of
headers might inadvertently be open to a header splitting attack. This is partly
why I suggested that we at least treat invalid mediatypes the same as we treat
empty mediatypes.

[tyoshino (SeeGerritForStatus), 2014/09/24 05:43:29]

Good point. It's been a while since I added this check. So, there could be some
new code that depends on this check.

OK. I'll make it fall back to the default ("text/plain") when the media type is
invalid instead of returning false.

-    return false;
   }
   if (charset->empty())
     charset->assign("US-ASCII");
 
   // The caller may not be interested in receiving the data.
   if (!data)
     return true;
 
   // Preserve spaces if dealing with text or xml input, same as mozilla:
   //   https://bugzilla.mozilla.org/show_bug.cgi?id=138052
@@ skipping 40 matching lines @@
       temp_data.resize(length + padding_needed, '=');
     }
     return base::Base64Decode(temp_data, data);
   }
 
   temp_data.swap(*data);
   return true;
 }
 
 }  // namespace net