wmall: use AVFrame API properly

This fixes a bug with non-refcounted callers resulting in invalid memory access.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/wmalosslessdec.c

@@ -66,7 +66,7 @@ typedef struct {
 typedef struct WmallDecodeCtx {
     /* generic decoder variables */
     AVCodecContext  *avctx;
-    AVFrame         frame;
+    AVFrame         *frame;
     uint8_t         frame_data[MAX_FRAMESIZE + FF_INPUT_BUFFER_PADDING_SIZE];  ///< compressed frame data
     PutBitContext   pb;                             ///< context for filling the frame_data buffer
 
@@ -261,8 +261,10 @@ static av_cold int decode_init(AVCodecContext *avctx)
         return AVERROR_PATCHWELCOME;
     }
 
-    avcodec_get_frame_defaults(&s->frame);
-    avctx->coded_frame    = &s->frame;
+    s->frame = av_frame_alloc();
+    if (!s->frame)
+        return AVERROR(ENOMEM);
+
     avctx->channel_layout = channel_mask;
     return 0;
 }
@@ -908,7 +910,7 @@ static int decode_subframe(WmallDecodeCtx *s)
     } else if (!s->cdlms[0][0].order) {
         av_log(s->avctx, AV_LOG_DEBUG,
                "Waiting for seekable tile\n");
-        s->frame.nb_samples = 0;
+        av_frame_unref(s->frame);
         return -1;
     }
 
@@ -1015,8 +1017,8 @@ static int decode_frame(WmallDecodeCtx *s)
     GetBitContext* gb = &s->gb;
     int more_frames = 0, len = 0, i, ret;
 
-    s->frame.nb_samples = s->samples_per_frame;
-    if ((ret = ff_get_buffer(s->avctx, &s->frame, 0)) < 0) {
+    s->frame->nb_samples = s->samples_per_frame;
+    if ((ret = ff_get_buffer(s->avctx, s->frame, 0)) < 0) {
         /* return an error if no frame could be decoded at all */
         av_log(s->avctx, AV_LOG_ERROR,
                "not enough space for the output samples\n");
@@ -1024,8 +1026,8 @@ static int decode_frame(WmallDecodeCtx *s)
         return ret;
     }
     for (i = 0; i < s->num_channels; i++) {
-        s->samples_16[i] = (int16_t *)s->frame.extended_data[i];
-        s->samples_32[i] = (int32_t *)s->frame.extended_data[i];
+        s->samples_16[i] = (int16_t *)s->frame->extended_data[i];
+        s->samples_32[i] = (int32_t *)s->frame->extended_data[i];
     }
 
     /* get frame length */
@@ -1172,7 +1174,7 @@ static int decode_packet(AVCodecContext *avctx, void *data, int *got_frame_ptr,
     int buf_size       = avpkt->size;
     int num_bits_prev_frame, packet_sequence_number, spliced_packet;
 
-    s->frame.nb_samples = 0;
+    s->frame->nb_samples = 0;
 
     if (s->packet_done || s->packet_loss) {
         s->packet_done = 0;
@@ -1265,8 +1267,9 @@ static int decode_packet(AVCodecContext *avctx, void *data, int *got_frame_ptr,
         save_bits(s, gb, remaining_bits(s, gb), 0);
     }
 
-    *(AVFrame *)data = s->frame;
-    *got_frame_ptr   = s->frame.nb_samples > 0;
+    *got_frame_ptr   = s->frame->nb_samples > 0;
+    av_frame_move_ref(data, s->frame);
+
     s->packet_offset = get_bits_count(gb) & 7;
 
     return (s->packet_loss) ? AVERROR_INVALIDDATA : get_bits_count(gb) >> 3;
@@ -1281,16 +1284,26 @@ static void flush(AVCodecContext *avctx)
     s->frame_offset      = 0;
     s->next_packet_start = 0;
     s->cdlms[0][0].order = 0;
-    s->frame.nb_samples  = 0;
+    s->frame->nb_samples = 0;
     init_put_bits(&s->pb, s->frame_data, MAX_FRAMESIZE);
 }
 
+static av_cold int decode_close(AVCodecContext *avctx)
+{
+    WmallDecodeCtx *s = avctx->priv_data;
+
+    av_frame_free(&s->frame);
+
+    return 0;
+}
+
 AVCodec ff_wmalossless_decoder = {
     .name           = "wmalossless",
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = AV_CODEC_ID_WMALOSSLESS,
     .priv_data_size = sizeof(WmallDecodeCtx),
     .init           = decode_init,
+    .close          = decode_close,
     .decode         = decode_packet,
     .flush          = flush,
     .capabilities   = CODEC_CAP_SUBFRAMES | CODEC_CAP_DR1 | CODEC_CAP_DELAY,