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vc1dec: Do not allow field_mode to change after the first header

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This fixes out of array accesses.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Michael Niedermayer 2012-11-16 00:48:15 +01:00 committed by Martin Storsjö
parent ec7d002e55
commit 4162fc62b3
3 changed files with 14 additions and 6 deletions
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17
libavcodec/vc1.c
View File

@ -825,6 +825,7 @@ int ff_vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
int status;
int mbmodetab, imvtab, icbptab, twomvbptab, fourmvbptab; /* useful only for debugging */
int scale, shift, i; /* for initializing LUT for intensity compensation */
int field_mode, fcm;
v->p_frame_skipped = 0;
if (v->second_field) {
@ -836,19 +837,23 @@ int ff_vc1_parse_frame_header_adv(VC1Context *v, GetBitContext* gb)
goto parse_common_info;
}
v->field_mode = 0;
field_mode = 0;
if (v->interlace) {
v->fcm = decode012(gb);
if (v->fcm) {
if (v->fcm == ILACE_FIELD)
v->field_mode = 1;
fcm = decode012(gb);
if (fcm) {
if (fcm == ILACE_FIELD)
field_mode = 1;
if (!v->warn_interlaced++)
av_log(v->s.avctx, AV_LOG_ERROR,
"Interlaced frames/fields support is incomplete\n");
}
} else {
v->fcm = PROGRESSIVE;
fcm = PROGRESSIVE;
}
if (!v->first_pic_header_flag && v->field_mode != field_mode)
return AVERROR_INVALIDDATA;
v->field_mode = field_mode;
v->fcm = fcm;
if (v->field_mode) {
v->fptype = get_bits(gb, 3);

1
libavcodec/vc1.h
View File

@ -372,6 +372,7 @@ typedef struct VC1Context{
int qs_last; ///< if qpel has been used in the previous (tr.) picture
int bmvtype;
int frfd, brfd; ///< reference frame distance (forward or backward)
int first_pic_header_flag;
int pic_header_flag;
/** Frame decoding info for sprite modes */

2
libavcodec/vc1dec.c
View File

@ -5463,6 +5463,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
// do parse frame header
v->pic_header_flag = 0;
v->first_pic_header_flag = 1;
if (v->profile < PROFILE_ADVANCED) {
if (ff_vc1_parse_frame_header(v, &s->gb) < 0) {
goto err;
@ -5472,6 +5473,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
goto err;
}
}
v->first_pic_header_flag = 0;
if ((avctx->codec_id == AV_CODEC_ID_WMV3IMAGE || avctx->codec_id == AV_CODEC_ID_VC1IMAGE)
&& s->pict_type != AV_PICTURE_TYPE_I) {