[vlc-devel] [PATCH] h264_nal: prevent infinite loops in PPS slice parsing
RĂ©mi Denis-Courmont
remi at remlab.net
Mon Nov 27 19:18:07 CET 2017
If X_minus_one == UINT32_MAX, the for-loop condition is always true.
This patch uses X directly: parsing will be wrong anyway, but at
least it won't lead to an infinite busy loop.
---
modules/packetizer/h264_nal.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/modules/packetizer/h264_nal.c b/modules/packetizer/h264_nal.c
index dd3b270ed5..22fb99caf0 100644
--- a/modules/packetizer/h264_nal.c
+++ b/modules/packetizer/h264_nal.c
@@ -548,18 +548,19 @@ static bool h264_parse_picture_parameter_set_rbsp( bs_t *p_bs,
bs_skip( p_bs, 1 ); // entropy coding mode flag
p_pps->i_pic_order_present_flag = bs_read( p_bs, 1 );
- unsigned num_slice_groups_minus1 = bs_read_ue( p_bs );
- if( num_slice_groups_minus1 > 0 )
+
+ unsigned num_slice_groups = bs_read_ue( p_bs ) + 1;
+ if( num_slice_groups > 1 )
{
unsigned slice_group_map_type = bs_read_ue( p_bs );
if( slice_group_map_type == 0 )
{
- for( unsigned i=0; i <= num_slice_groups_minus1; i++ )
+ for( unsigned i = 0; i < num_slice_groups; i++ )
bs_read_ue( p_bs ); /* run_length_minus1[group] */
}
else if( slice_group_map_type == 2 )
{
- for( unsigned i=0; i <= num_slice_groups_minus1; i++ )
+ for( unsigned i = 0; i < num_slice_groups; i++ )
{
bs_read_ue( p_bs ); /* top_left[group] */
bs_read_ue( p_bs ); /* bottom_right[group] */
@@ -572,14 +573,14 @@ static bool h264_parse_picture_parameter_set_rbsp( bs_t *p_bs,
}
else if( slice_group_map_type == 6 )
{
- unsigned pic_size_in_maps_units_minus1 = bs_read_ue( p_bs );
+ unsigned pic_size_in_maps_units = bs_read_ue( p_bs ) + 1;
unsigned sliceGroupSize = 1;
- while(num_slice_groups_minus1 > 0)
+ while(num_slice_groups > 1)
{
sliceGroupSize++;
- num_slice_groups_minus1 >>= 1;
+ num_slice_groups = ((num_slice_groups - 1) >> 1) + 1;
}
- for( unsigned i=0; i <= pic_size_in_maps_units_minus1; i++ )
+ for( unsigned i = 0; i < pic_size_in_maps_units; i++ )
{
bs_read( p_bs, sliceGroupSize );
}
--
2.15.0
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