[FFmpeg-cvslog] proresdec_lgpl: explicitly check coff[3] against slice_data_size

[Andreas Cadhalpun]

ffmpeg | branch: release/3.1 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Wed Nov  9 23:49:46 2016 +0100| [727ec4acc471b167f8af5211e860e2def6d47d02] | committer: Andreas Cadhalpun

proresdec_lgpl: explicitly check coff[3] against slice_data_size

The implicit checks via v_data_size and a_data_size don't work in the case
'(hdr_size > 7) && !ctx->alpha_info'.

This fixes segmentation faults due to invalid reads.

This problem was introduced in commit
547c2f002a87f4412a83c23b0d60364be5e7ce58.

Reviewed-by: Michael Niedermayer <michael at niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit 1e33035ee7a8d9fb7a4b8b6cc54842e72b36ed70)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=727ec4acc471b167f8af5211e860e2def6d47d02
---

 libavcodec/proresdec_lgpl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/proresdec_lgpl.c b/libavcodec/proresdec_lgpl.c
index 467a423..bc5bdb5 100644
--- a/libavcodec/proresdec_lgpl.c
+++ b/libavcodec/proresdec_lgpl.c
@@ -625,7 +625,7 @@ static int decode_slice(AVCodecContext *avctx, void *tdata)
 
     /* if V or alpha component size is negative that means that previous
        component sizes are too large */
-    if (v_data_size < 0 || a_data_size < 0 || hdr_size < 6) {
+    if (v_data_size < 0 || a_data_size < 0 || hdr_size < 6 || coff[3] > slice_data_size) {
         av_log(avctx, AV_LOG_ERROR, "invalid data size\n");
         return AVERROR_INVALIDDATA;
     }