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

net/disk_cache/block_files.cc

Index: net/disk_cache/block_files.cc
diff --git a/net/disk_cache/block_files.cc b/net/disk_cache/block_files.cc
index cd7e5cffb064d19a5df87e75caaf5009933f2687..0e9eb04ac5e82dddfb4e2b151f631827f4a5d647 100644
--- a/net/disk_cache/block_files.cc
+++ b/net/disk_cache/block_files.cc
@@ -247,6 +247,12 @@ bool BlockFiles::OpenBlockFile(int index) {
     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());