Minor defense-in-depth tweak. end - start + 1 can actually go negative if...

net/http/partial_data.cc

 // Copyright (c) 2009 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.
 
 #include "net/http/partial_data.h"
 
 #include "base/logging.h"
 #include "base/string_util.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/disk_cache.h"
@@ skipping 175 matching lines @@
            byte_range_.HasLastBytePosition();
   }
 
   int64 start, end, total_length;
   if (!headers->GetContentRange(&start, &end, &total_length))
     return false;
   if (total_length <= 0)
     return false;
 
   int64 content_length = headers->GetContentLength();
-  if (content_length != end - start + 1)
+  if (content_length < 0 || content_length != end - start + 1)
     return false;
 
   if (!resource_size_) {
     // First response. Update our values with the ones provided by the server.
     resource_size_ = total_length;
     if (!byte_range_.HasFirstBytePosition()) {
       byte_range_.set_first_byte_position(start);
       current_range_start_ = start;
     }
     if (!byte_range_.HasLastBytePosition())
@@ skipping 103 matching lines @@
   if (start >= 0)
     my_start = Int64ToString(start);
   if (end >= 0)
     my_end = Int64ToString(end);
 
   headers->append(StringPrintf("Range: bytes=%s-%s\r\n", my_start.c_str(),
                                my_end.c_str()));
 }
 
 }  // namespace net