lavf/img2dec: Fix memory leak

Fixes #4886

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 01dd7e025c)

libavformat/img2dec.c

@@ -440,14 +440,17 @@ int ff_img_read_packet(AVFormatContext *s1, AVPacket *pkt)
     }
 
     res = av_new_packet(pkt, size[0] + size[1] + size[2]);
-    if (res < 0)
-        return res;
+    if (res < 0) {
+        goto fail;
+    }
     pkt->stream_index = 0;
     pkt->flags       |= AV_PKT_FLAG_KEY;
     if (s->ts_from_file) {
         struct stat img_stat;
-        if (stat(filename, &img_stat))
-            return AVERROR(EIO);
+        if (stat(filename, &img_stat)) {
+            res = AVERROR(EIO);
+            goto fail;
+        }
         pkt->pts = (int64_t)img_stat.st_mtime;
 #if HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
         if (s->ts_from_file == 2)
@@ -481,18 +484,29 @@ int ff_img_read_packet(AVFormatContext *s1, AVPacket *pkt)
     if (ret[0] <= 0 || ret[1] < 0 || ret[2] < 0) {
         av_free_packet(pkt);
         if (ret[0] < 0) {
-            return ret[0];
+            res = ret[0];
         } else if (ret[1] < 0) {
-            return ret[1];
-        } else if (ret[2] < 0)
-            return ret[2];
-        return AVERROR_EOF;
+            res = ret[1];
+        } else if (ret[2] < 0) {
+            res = ret[2];
+        } else {
+            res = AVERROR_EOF;
+        }
+        goto fail;
     } else {
         s->img_count++;
         s->img_number++;
         s->pts++;
         return 0;
     }
+
+fail:
+    if (!s->is_pipe) {
+        for (i = 0; i < 3; i++) {
+            avio_closep(&f[i]);
+        }
+    }
+    return res;
 }
 
 static int img_read_close(struct AVFormatContext* s1)