Try again: Check blockfile size before attempting to read the header.

net/disk_cache/block_files.cc

 // Copyright (c) 2006-2008 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/disk_cache/block_files.h"
 
 #include "base/file_util.h"
 #include "base/histogram.h"
 #include "base/string_util.h"
 #include "base/time.h"
@@ skipping 229 matching lines @@
   MappedFile* file = new MappedFile();
   file->AddRef();
 
   if (!file->Init(name, kBlockHeaderSize)) {
     NOTREACHED();
     LOG(ERROR) << "Failed to open " << name;
     file->Release();
     return false;
   }
 
+  if (file->GetLength() < static_cast<size_t>(kBlockHeaderSize)) {
+    LOG(ERROR) << "File too small " << name;
+    file->Release();
+    return false;
+  }
+
   block_files_[index] = file;
 
   BlockFileHeader* header = reinterpret_cast<BlockFileHeader*>(file->buffer());
   if (kBlockMagic != header->magic || kCurrentVersion != header->version) {
     LOG(ERROR) << "Invalid file version or magic";
     return false;
   }
 
   if (header->updating) {
     // Last instance was not properly shutdown.
@@ skipping 219 matching lines @@
     int num_entries = (file_size - sizeof(*header)) / header->entry_size;
     header->max_entries = num_entries;
   }
 
   FixAllocationCounters(header);
   header->updating = 0;
   return true;
 }
 
 }  // namespace disk_cache