avcodec/textdec: add some memory checks

libavcodec/textdec.c

@@ -44,6 +44,7 @@ static const AVOption options[] = {
 static int text_decode_frame(AVCodecContext *avctx, void *data,
                              int *got_sub_ptr, AVPacket *avpkt)
 {
+    int ret = 0;
     AVBPrint buf;
     AVSubtitle *sub = data;
     const char *ptr = avpkt->data;
@@ -55,14 +56,12 @@ static int text_decode_frame(AVCodecContext *avctx, void *data,
     av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
     if (ptr && avpkt->size > 0 && *ptr) {
         ff_ass_bprint_text_event(&buf, ptr, avpkt->size, text->linebreaks, text->keep_ass_markup);
-        if (!av_bprint_is_complete(&buf)) {
-            av_bprint_finalize(&buf, NULL);
-            return AVERROR(ENOMEM);
-        }
-        ff_ass_add_rect(sub, buf.str, ts_start, ts_duration, 0);
+        ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_duration, 0);
     }
-    *got_sub_ptr = sub->num_rects > 0;
     av_bprint_finalize(&buf, NULL);
+    if (ret < 0)
+        return ret;
+    *got_sub_ptr = sub->num_rects > 0;
     return avpkt->size;
 }