From c8d839df73196a9a5a03b75a12467e6e33d306f7 Mon Sep 17 00:00:00 2001
From: Martijn van Beurden <mvanb1@gmail.com>
Date: Sat, 11 Jun 2022 09:32:16 +0200
Subject: [PATCH] avformat/mov: prevent potential use of uninitialized value

---
 libavformat/mov.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavformat/mov.c b/libavformat/mov.c
index 88669faa70..5d8b24368a 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -6797,7 +6797,10 @@ static int mov_read_dfla(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     avio_rb24(pb); /* Flags */
 
-    avio_read(pb, buf, sizeof(buf));
+    if (avio_read(pb, buf, sizeof(buf)) != sizeof(buf)) {
+        av_log(c->fc, AV_LOG_ERROR, "failed to read FLAC metadata block header\n");
+        return pb->error < 0 ? pb->error : AVERROR_INVALIDDATA;
+    }
     flac_parse_block_header(buf, &last, &type, &size);
 
     if (type != FLAC_METADATA_TYPE_STREAMINFO || size != FLAC_STREAMINFO_SIZE) {