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

[Andreas Cadhalpun]

ffmpeg | branch: master | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Wed Nov 11 00:20:18 2015 +0100| [9a37d476440d9edaa26e6ed946d79cedde9d9e93] | committer: Andreas Cadhalpun

dds: validate compressed source buffer size

A too small buffer will cause segfaults somewhere below
decompress_texture_thread.

Reviewed-by: Vittorio Giovara <vittorio.giovara at gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9a37d476440d9edaa26e6ed946d79cedde9d9e93
---

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

diff --git a/libavcodec/dds.c b/libavcodec/dds.c
index 324e665..c918cf0 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);