diff --git a/media/extractors/mp4/MPEG4Extractor.cpp b/media/extractors/mp4/MPEG4Extractor.cpp
index 8836c47..65c0238 100644
--- a/media/extractors/mp4/MPEG4Extractor.cpp
+++ b/media/extractors/mp4/MPEG4Extractor.cpp
@@ -4771,7 +4771,7 @@
         if (len2 == 0) {
             return ERROR_MALFORMED;
         }
-        if (offset >= csd_size || csd[offset] != 0x01) {
+        if (offset + len1 > csd_size || csd[offset] != 0x01) {
             return ERROR_MALFORMED;
         }