mpegvideo: set correct offset for edge emulation buffer.

Using the old code, half of it was unused and the other half was too
small for e.g. >8bpp interlaced data, causing random buffer overruns.

1 files changed, 2 insertions, 4 deletions

diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index baab3c85e6..b8ac2ceb3d 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -377,8 +377,7 @@ static int init_duplicate_context(MpegEncContext *s, MpegEncContext *base){
     int i;
 
     // edge emu needs blocksize + filter length - 1 (=17x17 for halfpel / 21x21 for h264)
-    FF_ALLOCZ_OR_GOTO(s->avctx, s->allocated_edge_emu_buffer, (s->width+64)*2*21*2, fail); //(width + edge + align)*interlaced*MBsize*tolerance
-    s->edge_emu_buffer= s->allocated_edge_emu_buffer + (s->width+64)*2*21;
+    FF_ALLOCZ_OR_GOTO(s->avctx, s->edge_emu_buffer, (s->width+64)*2*21*2, fail); //(width + edge + align)*interlaced*MBsize*tolerance
 
      //FIXME should be linesize instead of s->width*2 but that is not known before get_buffer()
     FF_ALLOCZ_OR_GOTO(s->avctx, s->me.scratchpad,  (s->width+64)*4*16*2*sizeof(uint8_t), fail)
@@ -416,7 +415,7 @@ fail:
 static void free_duplicate_context(MpegEncContext *s){
     if(s==NULL) return;
 
-    av_freep(&s->allocated_edge_emu_buffer); s->edge_emu_buffer= NULL;
+    av_freep(&s->edge_emu_buffer);
     av_freep(&s->me.scratchpad);
     s->me.temp=
     s->rd_scratchpad=
@@ -433,7 +432,6 @@ static void free_duplicate_context(MpegEncContext *s){
 
 static void backup_duplicate_context(MpegEncContext *bak, MpegEncContext *src){
 #define COPY(a) bak->a= src->a
-    COPY(allocated_edge_emu_buffer);
     COPY(edge_emu_buffer);
     COPY(me.scratchpad);
     COPY(me.temp);