From e0d8a17402b934b8fba7b86c6c990abf1257901b Mon Sep 17 00:00:00 2001 From: Anton Khirnov Date: Fri, 15 Nov 2013 19:06:23 +0100 Subject: [PATCH] h264_refs: make sure not to write over the bounds of the default ref list Fixes invalid writes. Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind CC:libav-stable@libav.org --- libavcodec/h264_refs.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) diff --git a/libavcodec/h264_refs.c b/libavcodec/h264_refs.c index 273c52b475..dd4bd62206 100644 --- a/libavcodec/h264_refs.c +++ b/libavcodec/h264_refs.c @@ -62,20 +62,22 @@ static int split_field_copy(Picture *dest, Picture *src, return match; } -static int build_def_list(Picture *def, Picture **in, int len, int is_long, int sel){ +static int build_def_list(Picture *def, int def_len, + Picture **in, int len, int is_long, int sel) +{ int i[2]={0}; int index=0; - while(i[0]f.reference & sel))) i[0]++; while (i[1] < len && !(in[ i[1] ] && (in[ i[1] ]->f.reference & (sel^3)))) i[1]++; - if(i[0] < len){ + if (i[0] < len && index < def_len) { in[ i[0] ]->pic_id= is_long ? i[0] : in[ i[0] ]->frame_num; split_field_copy(&def[index++], in[ i[0]++ ], sel , 1); } - if(i[1] < len){ + if (i[1] < len && index < def_len) { in[ i[1] ]->pic_id= is_long ? i[1] : in[ i[1] ]->frame_num; split_field_copy(&def[index++], in[ i[1]++ ], sel^3, 0); } @@ -123,9 +125,12 @@ int ff_h264_fill_default_ref_list(H264Context *h){ len= add_sorted(sorted , h->short_ref, h->short_ref_count, cur_poc, 1^list); len+=add_sorted(sorted+len, h->short_ref, h->short_ref_count, cur_poc, 0^list); assert(len<=32); - len= build_def_list(h->default_ref_list[list] , sorted , len, 0, s->picture_structure); - len+=build_def_list(h->default_ref_list[list]+len, h->long_ref, 16 , 1, s->picture_structure); - assert(len<=32); + + len = build_def_list(h->default_ref_list[list], FF_ARRAY_ELEMS(h->default_ref_list[0]), + sorted, len, 0, s->picture_structure); + len += build_def_list(h->default_ref_list[list] + len, + FF_ARRAY_ELEMS(h->default_ref_list[0]) - len, + h->long_ref, 16, 1, s->picture_structure); if(len < h->ref_count[list]) memset(&h->default_ref_list[list][len], 0, sizeof(Picture)*(h->ref_count[list] - len)); @@ -138,9 +143,12 @@ int ff_h264_fill_default_ref_list(H264Context *h){ FFSWAP(Picture, h->default_ref_list[1][0], h->default_ref_list[1][1]); } }else{ - len = build_def_list(h->default_ref_list[0] , h->short_ref, h->short_ref_count, 0, s->picture_structure); - len+= build_def_list(h->default_ref_list[0]+len, h-> long_ref, 16 , 1, s->picture_structure); - assert(len <= 32); + len = build_def_list(h->default_ref_list[0], FF_ARRAY_ELEMS(h->default_ref_list[0]), + h->short_ref, h->short_ref_count, 0, s->picture_structure); + len += build_def_list(h->default_ref_list[0] + len, + FF_ARRAY_ELEMS(h->default_ref_list[0]) - len, + h-> long_ref, 16, 1, s->picture_structure); + if(len < h->ref_count[0]) memset(&h->default_ref_list[0][len], 0, sizeof(Picture)*(h->ref_count[0] - len)); }