[FFmpeg-cvslog] dds: validate compressed source buffer size

[Andreas Cadhalpun]

ffmpeg | branch: master | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Wed Nov 11 01:15:55 2015 +0100| [29b17528612c8b0f66e6982ab48cc0816e41f36f] | committer: Vittorio Giovara

dds: validate compressed source buffer size

A too small buffer will cause segfaults somewhere below
decompress_texture_thread.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=29b17528612c8b0f66e6982ab48cc0816e41f36f
---

 libavcodec/dds.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/libavcodec/dds.c b/libavcodec/dds.c
index 0f045d6..2196124 100644
--- a/libavcodec/dds.c
+++ b/libavcodec/dds.c
@@ -642,9 +642,18 @@ static int dds_decode(AVCodecContext *avctx, void *data,
         return ret;
 
     if (ctx->compressed) {
+        int size = (avctx->coded_height / TEXTURE_BLOCK_H) *
+                   (avctx->coded_width / TEXTURE_BLOCK_W) * ctx->tex_ratio;
         ctx->slice_count = av_clip(avctx->thread_count, 1,
                                    avctx->coded_height / TEXTURE_BLOCK_H);
 
+        if (bytestream2_get_bytes_left(gbc) < size) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Compressed Buffer is too small (%d < %d).\n",
+                   bytestream2_get_bytes_left(gbc), size);
+            return AVERROR_INVALIDDATA;
+        }
+
         /* Use the decompress function on the texture, one block per thread. */
         ctx->tex_data = gbc->buffer;
         avctx->execute2(avctx, decompress_texture_thread, frame, NULL, ctx->slice_count);