avcodec/atrac9dec: Check init_get_bits8() for failure

Fixes: CID1439569 Unchecked return value
Fixes: CID1439578 Unchecked return value

Sponsored-by: Sovereign Tech Fund
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 615c994739)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/atrac9dec.c

@@ -801,7 +801,9 @@ static int atrac9_decode_frame(AVCodecContext *avctx, AVFrame *frame,
     if (ret < 0)
         return ret;
 
-    init_get_bits8(&gb, avpkt->data, avpkt->size);
+    ret = init_get_bits8(&gb, avpkt->data, avpkt->size);
+    if (ret < 0)
+        return ret;
 
     for (int i = 0; i < frames; i++) {
         for (int j = 0; j < s->block_config->count; j++) {
@@ -921,7 +923,9 @@ static av_cold int atrac9_decode_init(AVCodecContext *avctx)
         return AVERROR_INVALIDDATA;
     }
 
-    init_get_bits8(&gb, avctx->extradata + 4, avctx->extradata_size);
+    err = init_get_bits8(&gb, avctx->extradata + 4, avctx->extradata_size);
+    if (err < 0)
+        return err;
 
     if (get_bits(&gb, 8) != 0xFE) {
         av_log(avctx, AV_LOG_ERROR, "Incorrect magic byte!\n");