From 3391bd80c423a024cd19af7db68bbc3f41dccbd9 Mon Sep 17 00:00:00 2001
From: bobsayshilol <bobsayshilol@live.co.uk>
Date: Sat, 24 Apr 2021 15:56:52 +0100
Subject: [PATCH] FLAC: Validate the size of a read

Without this we can crash trying to dereference parts of `header`.
---
 taglib/flac/flacfile.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/taglib/flac/flacfile.cpp b/taglib/flac/flacfile.cpp
index ada215db..6ecd3bad 100644
--- a/taglib/flac/flacfile.cpp
+++ b/taglib/flac/flacfile.cpp
@@ -497,6 +497,11 @@ void FLAC::File::scan()
 
     seek(nextBlockOffset);
     const ByteVector header = readBlock(4);
+    if(header.size() != 4) {
+      debug("FLAC::File::scan() -- Failed to read a block header");
+      setValid(false);
+      return;
+    }
 
     // Header format (from spec):
     // <1> Last-metadata-block flag