avformat/mxfdec: Check for avio_read() failure in mxf_read_strong_ref_array()

Fixes: 42827/clusterfuzz-testcase-minimized-ffmpeg_dem_MXF_fuzzer-4900528511909888

Reviewed-by: Tomas Härdin <tjoppen@acc.umu.se>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/mxfdec.c

@@ -933,6 +933,7 @@ static int mxf_read_cryptographic_context(void *arg, AVIOContext *pb, int tag, i
 
 static int mxf_read_strong_ref_array(AVIOContext *pb, UID **refs, int *count)
 {
+    int64_t ret;
     unsigned c = avio_rb32(pb);
 
     //avio_read() used int
@@ -947,7 +948,12 @@ static int mxf_read_strong_ref_array(AVIOContext *pb, UID **refs, int *count)
         return AVERROR(ENOMEM);
     }
     avio_skip(pb, 4); /* useless size of objects, always 16 according to specs */
-    avio_read(pb, (uint8_t *)*refs, *count * sizeof(UID));
+    ret = avio_read(pb, (uint8_t *)*refs, *count * sizeof(UID));
+    if (ret != *count * sizeof(UID)) {
+        *count = ret < 0 ? 0   : ret / sizeof(UID);
+        return   ret < 0 ? ret : AVERROR_INVALIDDATA;
+    }
+
     return 0;
 }