avfilter/asubprocess: add more out-of-memory checks

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

libavfilter/af_asubprocess.c

@@ -80,6 +80,8 @@ static SPB *spb_new(AVFilterContext *ctx)
     }
     else {
         spb = av_malloc(sizeof(SPB));
+        if (!spb)
+            return NULL;
     }
 
     spb->next = NULL;
@@ -355,8 +357,11 @@ sp_write(AVFilterContext *ctx, char *buffer, int count)
             SPB *last;
             int rc, ret;
 
-            if (!sp->out_buffers)
+            if (!sp->out_buffers) {
                 sp->out_buffers = spb_new(ctx);
+                if (!sp->out_buffers)
+                    return AVERROR(ENOMEM);
+            }
 
             last = sp->out_buffers;
             while (last->next)
@@ -364,6 +369,8 @@ sp_write(AVFilterContext *ctx, char *buffer, int count)
 
             if (last->count == sizeof(last->data)) {
                 last->next = spb_new(ctx);
+                if (!last->next)
+                    return AVERROR(ENOMEM);
                 last = last->next;
             }
             rc = read(sp->output_pipe, last->data + last->count, sizeof(last->data) - last->count);