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

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Fixes out of array accesses.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-11-16 00:48:15 +01:00
parent 8f42b09604
commit 7845f8d282
3 changed files with 14 additions and 6 deletions
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17
libavcodec/vc1.c
View File

@ -834,6 +834,7 @@ 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->numref=0;
v->p_frame_skipped = 0;
@ -848,19 +849,23 @@ 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 -1;
v->field_mode = field_mode;
v->fcm = fcm;
if (v->field_mode) {
v->fptype = get_bits(gb, 3);

1
libavcodec/vc1.h
View File

@ -368,6 +368,7 @@ 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

@ -5516,6 +5516,7 @@ 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;
@ -5525,6 +5526,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data,
goto err;
}
}
v->first_pic_header_flag = 0;
if (avctx->debug & FF_DEBUG_PICT_INFO)
av_log(v->s.avctx, AV_LOG_DEBUG, "pict_type: %c\n", av_get_picture_type_char(s->pict_type));