avfilter/vf_extractplanes: check ff_insert_outpad() for failure

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/vf_extractplanes.c

@@ -348,7 +348,7 @@ static av_cold int init(AVFilterContext *ctx)
 {
     ExtractPlanesContext *s = ctx->priv;
     int planes = (s->requested_planes & 0xf) | (s->requested_planes >> 4);
-    int i;
+    int i, ret;
 
     for (i = 0; i < 4; i++) {
         char *name;
@@ -365,7 +365,10 @@ static av_cold int init(AVFilterContext *ctx)
         pad.type = AVMEDIA_TYPE_VIDEO;
         pad.config_props = config_output;
 
-        ff_insert_outpad(ctx, ctx->nb_outputs, &pad);
+        if ((ret = ff_insert_outpad(ctx, ctx->nb_outputs, &pad)) < 0) {
+            av_freep(&pad.name);
+            return ret;
+        }
     }
 
     return 0;