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h264: Improve first slice and slice type checks 

This prevents a null pointer dereference

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-12-17 00:48:33 +01:00
parent 55b243cade
commit 7973a07590
1 changed files with 13 additions and 2 deletions
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15
libavcodec/h264.c
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@ -3790,6 +3790,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
int nals_needed = 0; ///< number of NALs that need decoding before the next frame thread starts
int nal_index;
int idr_cleared=0;
int first_slice = 0;
h->nal_unit_type= 0;
@ -3900,12 +3901,22 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
case NAL_IDR_SLICE:
case NAL_SLICE:
init_get_bits(&hx->s.gb, ptr, bit_length);
if (!get_ue_golomb(&hx->s.gb))
if (!get_ue_golomb(&hx->s.gb) || !first_slice)
nals_needed = nal_index;
if (!first_slice)
first_slice = hx->nal_unit_type;
}
continue;
}
if (!first_slice)
switch (hx->nal_unit_type) {
case NAL_DPA:
case NAL_IDR_SLICE:
case NAL_SLICE:
first_slice = hx->nal_unit_type;
}
// FIXME do not discard SEI id
if (avctx->skip_frame >= AVDISCARD_NONREF && h->nal_ref_idc == 0)
continue;
@ -3928,7 +3939,7 @@ again:
switch (hx->nal_unit_type) {
case NAL_IDR_SLICE:
if (h->nal_unit_type != NAL_IDR_SLICE) {
if (first_slice != NAL_IDR_SLICE) {
av_log(h->s.avctx, AV_LOG_ERROR,
"Invalid mix of idr and non-idr slices\n");
buf_index = -1;