[FFmpeg-cvslog] mpeg4videodec: Check the width/height in mpeg4_decode_sprite_trajectory

[Martin Storsjö]

ffmpeg | branch: master | Martin Storsjö <martin at martin.st> | Mon Sep 16 20:40:13 2013 +0300| [f875a732e36786d49f3650e3235272891a820600] | committer: Martin Storsjö

mpeg4videodec: Check the width/height in mpeg4_decode_sprite_trajectory

This avoids a potential division by zero.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable at libav.org
Signed-off-by: Martin Storsjö <martin at martin.st>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f875a732e36786d49f3650e3235272891a820600
---

 libavcodec/mpeg4videodec.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
index ca937da..8760ab7 100644
--- a/libavcodec/mpeg4videodec.c
+++ b/libavcodec/mpeg4videodec.c
@@ -154,7 +154,7 @@ static inline int mpeg4_is_resync(MpegEncContext *s){
     return 0;
 }
 
-static void mpeg4_decode_sprite_trajectory(MpegEncContext * s, GetBitContext *gb)
+static int mpeg4_decode_sprite_trajectory(MpegEncContext *s, GetBitContext *gb)
 {
     int i;
     int a= 2<<s->sprite_warping_accuracy;
@@ -170,6 +170,9 @@ static void mpeg4_decode_sprite_trajectory(MpegEncContext * s, GetBitContext *gb
     int h= s->height;
     int min_ab;
 
+    if (w <= 0 || h <= 0)
+        return AVERROR_INVALIDDATA;
+
     for(i=0; i<s->num_sprite_warping_points; i++){
         int length;
         int x=0, y=0;
@@ -342,6 +345,7 @@ static void mpeg4_decode_sprite_trajectory(MpegEncContext * s, GetBitContext *gb
         }
         s->real_sprite_warping_points= s->num_sprite_warping_points;
     }
+    return 0;
 }
 
 /**
@@ -416,7 +420,8 @@ int ff_mpeg4_decode_video_packet_header(MpegEncContext *s)
             skip_bits(&s->gb, 3); /* intra dc vlc threshold */
 //FIXME don't just ignore everything
             if(s->pict_type == AV_PICTURE_TYPE_S && s->vol_sprite_usage==GMC_SPRITE){
-                mpeg4_decode_sprite_trajectory(s, &s->gb);
+                if (mpeg4_decode_sprite_trajectory(s, &s->gb) < 0)
+                    return AVERROR_INVALIDDATA;
                 av_log(s->avctx, AV_LOG_ERROR, "untested\n");
             }
 
@@ -2031,7 +2036,8 @@ static int decode_vop_header(MpegEncContext *s, GetBitContext *gb){
      }
 
      if(s->pict_type == AV_PICTURE_TYPE_S && (s->vol_sprite_usage==STATIC_SPRITE || s->vol_sprite_usage==GMC_SPRITE)){
-         mpeg4_decode_sprite_trajectory(s, gb);
+         if (mpeg4_decode_sprite_trajectory(s, gb) < 0)
+             return AVERROR_INVALIDDATA;
          if(s->sprite_brightness_change) av_log(s->avctx, AV_LOG_ERROR, "sprite_brightness_change not supported\n");
          if(s->vol_sprite_usage==STATIC_SPRITE) av_log(s->avctx, AV_LOG_ERROR, "static sprite not supported\n");
      }