From 8f52da3288903e68c286c50e0b8b4f6a571e772a Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Sun, 29 Dec 2024 13:48:05 +0100
Subject: [PATCH] Issue #2673 - Part 2b: Improve ADTS format sniffer's
 performance.

Also avoids false positives.
---
 dom/media/ADTSDemuxer.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dom/media/ADTSDemuxer.cpp b/dom/media/ADTSDemuxer.cpp
index cb4fe61541..16daac6d4e 100644
--- a/dom/media/ADTSDemuxer.cpp
+++ b/dom/media/ADTSDemuxer.cpp
@@ -846,6 +846,10 @@ ADTSDemuxer::ADTSSniffer(const uint8_t* aData, const uint32_t aLength)
   if (aLength < 7) {
     return false;
   }
+  // Avoid seeking if blob doesn't start with an ADTS marker.
+  if (!adts::FrameHeader::MatchesSync(aData)) {
+    return false;
+  }
   auto parser = MakeUnique<adts::FrameParser>();
 
   if (!parser->Parse(0, aData, aData + aLength)) {