Improve data sanitization of initialization data

media/blink/webcontentdecryptionmodulesession_impl.cc

Index: media/blink/webcontentdecryptionmodulesession_impl.cc
diff --git a/media/blink/webcontentdecryptionmodulesession_impl.cc b/media/blink/webcontentdecryptionmodulesession_impl.cc
index d8ae46335f44b640d10b3d39eaddda15c24222ca..1a2b21c92e1877f31df8d221bfcdee37aaa8e20c 100644
--- a/media/blink/webcontentdecryptionmodulesession_impl.cc
+++ b/media/blink/webcontentdecryptionmodulesession_impl.cc
@@ -104,6 +104,7 @@ static bool SanitizeInitData(EmeInitDataType init_data_type,
                              size_t init_data_length,
                              std::vector<uint8_t>* sanitized_init_data,
                              std::string* error_message) {
+  DCHECK_GT(init_data_length, 0u);
   if (init_data_length > limits::kMaxInitDataLength) {
     error_message->assign("Initialization data too long.");
     return false;
@@ -111,6 +112,11 @@ static bool SanitizeInitData(EmeInitDataType init_data_type,
 
   switch (init_data_type) {
     case EmeInitDataType::WEBM:
+      // |init_data| for WebM is a single key.
+      if (init_data_length > limits::kMaxKeyIdLength) {
+        error_message->assign("Initialization data for WebM is too long.");
+        return false;
+      }
       sanitized_init_data->assign(init_data, init_data + init_data_length);
       return true;