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Code Issues Releases Activity

lavc/vvc: Add max parameter to kth_order_egk_decode

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Prior to this patch, kth_order_egk_decode could read arbitrarily
large values which then overflowed and caused various issues.
Patch fixes this by making kth_order_egk_decode falliable,
requiring the caller to specify an upper bound and returning an
error if the read value would exceed that bound.

This patch resolves the same issue as
eb52251c0a, but I think this is the proper
fix as it also addresses issues with syntax elements besides
ff_vvc_num_signalled_palette_entries.

Signed-off-by: Frank Plowman <post@frankplowman.com>
This commit is contained in:
Frank Plowman
2025-07-19 18:16:25 +01:00
parent ce172bc362
commit 7c5319e692
3 changed files with 25 additions and 19 deletions
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19
libavcodec/vvc/cabac.c
View File

@ -929,7 +929,7 @@ static int truncated_binary_decode(VVCLocalContext *lc, const int c_max)
}
// 9.3.3.5 k-th order Exp - Golomb binarization process
static int kth_order_egk_decode(CABACContext *c, int k)
static int kth_order_egk_decode(CABACContext *c, int k, const int max)
{
int bit = 1;
int value = 0;
@ -937,6 +937,8 @@ static int kth_order_egk_decode(CABACContext *c, int k)
while (bit) {
bit = get_cabac_bypass(c);
if (max - value < (bit << k))
return AVERROR_INVALIDDATA;
value += bit << k++;
}
@ -946,6 +948,9 @@ static int kth_order_egk_decode(CABACContext *c, int k)
value += symbol;
}
if (value > max)
return AVERROR_INVALIDDATA;
return value;
}
@ -1377,14 +1382,14 @@ int ff_vvc_intra_chroma_pred_mode(VVCLocalContext *lc)
return (get_cabac_bypass(&lc->ep->cc) << 1) | get_cabac_bypass(&lc->ep->cc);
}
int ff_vvc_palette_predictor_run(VVCLocalContext *lc)
int ff_vvc_palette_predictor_run(VVCLocalContext *lc, const int max)
{
return kth_order_egk_decode(&lc->ep->cc, 0);
return kth_order_egk_decode(&lc->ep->cc, 0, max);
}
int ff_vvc_num_signalled_palette_entries(VVCLocalContext *lc)
int ff_vvc_num_signalled_palette_entries(VVCLocalContext *lc, const int max)
{
return kth_order_egk_decode(&lc->ep->cc, 0);
return kth_order_egk_decode(&lc->ep->cc, 0, max);
}
int ff_vvc_new_palette_entries(VVCLocalContext *lc, const int bit_depth)
@ -1424,9 +1429,9 @@ int ff_vvc_palette_idx_idc(VVCLocalContext *lc, const int max_palette_index, con
return truncated_binary_decode(lc, max_palette_index - adjust);
}
int ff_vvc_palette_escape_val(VVCLocalContext *lc)
int ff_vvc_palette_escape_val(VVCLocalContext *lc, const int max)
{
return kth_order_egk_decode(&lc->ep->cc, 5);
return kth_order_egk_decode(&lc->ep->cc, 5, max);
}
int ff_vvc_general_merge_flag(VVCLocalContext *lc)

6
libavcodec/vvc/cabac.h
View File

@ -81,15 +81,15 @@ int ff_vvc_intra_luma_mpm_remainder(VVCLocalContext *lc);
int ff_vvc_cclm_mode_flag(VVCLocalContext *lc);
int ff_vvc_cclm_mode_idx(VVCLocalContext *lc);
int ff_vvc_intra_chroma_pred_mode(VVCLocalContext *lc);
int ff_vvc_palette_predictor_run(VVCLocalContext *lc);
int ff_vvc_num_signalled_palette_entries(VVCLocalContext *lc);
int ff_vvc_palette_predictor_run(VVCLocalContext *lc, const int max);
int ff_vvc_num_signalled_palette_entries(VVCLocalContext *lc, const int max);
int ff_vvc_new_palette_entries(VVCLocalContext *lc, int bit_dpeth);
bool ff_vvc_palette_escape_val_present_flag(VVCLocalContext *lc);
bool ff_vvc_palette_transpose_flag(VVCLocalContext *lc);
bool ff_vvc_run_copy_flag(VVCLocalContext *lc, int prev_run_type, int prev_run_position, int cur_pos);
bool ff_vvc_copy_above_palette_indices_flag(VVCLocalContext *lc);
int ff_vvc_palette_idx_idc(VVCLocalContext *lc, int max_palette_index, bool adjust);
int ff_vvc_palette_escape_val(VVCLocalContext *lc);
int ff_vvc_palette_escape_val(VVCLocalContext *lc, const int max);
//inter
int ff_vvc_general_merge_flag(VVCLocalContext *lc);

19
libavcodec/vvc/ctu.c
View File

@ -20,6 +20,7 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/error.h"
#include "libavutil/refstruct.h"
#include "cabac.h"
@ -1857,16 +1858,16 @@ static int palette_predicted(VVCLocalContext *lc, const bool local_dual_tree, in
}
for (int i = 0; i < predictor_size && nb_predicted < max_entries; i++) {
const int run = ff_vvc_palette_predictor_run(lc);
const int run = ff_vvc_palette_predictor_run(lc, predictor_size - i);
if (run < 0)
return run;
if (run == 1)
break;
if (run > 1)
i += run - 1;
if (i >= predictor_size)
return AVERROR_INVALIDDATA;
predictor_reused[i] = true;
for (int c = start; c < end; c++)
cu->plt[c].entries[nb_predicted] = lc->ep->pp[c].entries[i];
@ -1885,11 +1886,11 @@ static int palette_signaled(VVCLocalContext *lc, const bool local_dual_tree,
const VVCSPS *sps = lc->fc->ps.sps;
CodingUnit *cu = lc->cu;
const int nb_predicted = cu->plt[start].size;
const int nb_signaled = nb_predicted < max_entries ? ff_vvc_num_signalled_palette_entries(lc) : 0;
const int nb_signaled = nb_predicted < max_entries ? ff_vvc_num_signalled_palette_entries(lc, max_entries - nb_predicted) : 0;
const int size = nb_predicted + nb_signaled;
const bool dual_tree_luma = local_dual_tree && cu->tree_type == DUAL_TREE_LUMA;
if (size > max_entries || nb_signaled < 0)
if (nb_signaled < 0)
return AVERROR_INVALIDDATA;
for (int c = start; c < end; c++) {
@ -2052,10 +2053,10 @@ static int palette_subblock_data(VVCLocalContext *lc,
if (!(xc & hs) && !(yc & vs)) {
const int v = PALETTE_INDEX(xc, yc);
if (v == esc) {
const int coeff = ff_vvc_palette_escape_val(lc);
if (coeff >= (1U << sps->bit_depth))
return AVERROR_INVALIDDATA;
const int coeff = ff_vvc_palette_escape_val(lc, (1 << sps->bit_depth) - 1);
const int pixel = av_clip_intp2(RSHIFT(coeff * scale, 6), sps->bit_depth);
if (coeff < 0)
return AVERROR_INVALIDDATA;
PALETTE_SET_PIXEL(xc, yc, pixel);
} else {
PALETTE_SET_PIXEL(xc, yc, plt->entries[v]);