Re: [FFmpeg-devel] [PATCH v1] lavc/vvc: Validate num_signalled_palette_entries

[Nuo Mi <nuomi2021@gmail.com>]

Hi Frank,
👍,your fuzzing infrastructure caught this issue as well.
How about this:
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20250517055150.807683-1-nuomi2021@gmail.com/

On Sun, May 18, 2025 at 5:05 AM Frank Plowman <post@frankplowman.com> wrote:

> "The value of CurrentPaletteSize[ startComp ] shall be in the range of 0
> to maxNumPaletteEntries, inclusive."
>
> Signed-off-by: Frank Plowman <post@frankplowman.com>
> ---
>  libavcodec/vvc/ctu.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/libavcodec/vvc/ctu.c b/libavcodec/vvc/ctu.c
> index 62c9d4f5c0..70800ba5fa 100644
> --- a/libavcodec/vvc/ctu.c
> +++ b/libavcodec/vvc/ctu.c
> @@ -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"
> @@ -1873,7 +1874,7 @@ static void palette_predicted(VVCLocalContext *lc,
> const bool local_dual_tree, i
>          cu->plt[c].size = nb_predicted;
>  }
>
> -static void palette_signaled(VVCLocalContext *lc, const bool
> local_dual_tree,
> +static int palette_signaled(VVCLocalContext *lc, const bool
> local_dual_tree,
>      const int start, const int end, const int max_entries)
>  {
>      const VVCSPS *sps         = lc->fc->ps.sps;
> @@ -1883,6 +1884,9 @@ static void palette_signaled(VVCLocalContext *lc,
> const bool local_dual_tree,
>      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)
> +        return AVERROR_INVALIDDATA;
> +
>      for (int c = start; c < end; c++) {
>          Palette *plt = cu->plt + c;
>          for (int i = nb_predicted; i < size; i++) {
> @@ -1894,6 +1898,8 @@ static void palette_signaled(VVCLocalContext *lc,
> const bool local_dual_tree,
>          }
>          plt->size = size;
>      }
> +
> +    return 0;
>  }
>
>  static void palette_update_predictor(VVCLocalContext *lc, const bool
> local_dual_tree, int start, int end,
> @@ -2070,7 +2076,7 @@ static int hls_palette_coding(VVCLocalContext *lc,
> const VVCTreeType tree_type)
>      int max_index                 = 0;
>      int prev_run_pos              = 0;
>
> -    int predictor_size, start, end;
> +    int predictor_size, start, end, ret;
>      bool reused[VVC_MAX_NUM_PALETTE_PREDICTOR_SIZE];
>      uint8_t run_type[MAX_PALETTE_CU_SIZE * MAX_PALETTE_CU_SIZE];
>      uint8_t index[MAX_PALETTE_CU_SIZE * MAX_PALETTE_CU_SIZE];
> @@ -2083,7 +2089,9 @@ static int hls_palette_coding(VVCLocalContext *lc,
> const VVCTreeType tree_type)
>      predictor_size = pp[start].size;
>      memset(reused, 0, sizeof(reused[0]) * predictor_size);
>      palette_predicted(lc, local_dual_tree, start, end, reused,
> predictor_size, max_entries);
> -    palette_signaled(lc, local_dual_tree, start, end, max_entries);
> +    ret = palette_signaled(lc, local_dual_tree, start, end, max_entries);
> +    if (ret < 0)
> +        return ret;
>      palette_update_predictor(lc, local_dual_tree, start, end, reused,
> predictor_size);
>
>      if (cu->plt[start].size > 0)
> --
> 2.47.0
>
>
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