[FFmpeg-devel] [PATCH] avcodec/jpeg2000dec: fix tilepart processing

[Pierre-Anthony Lemieux]

LGTM. Will merge over the weekend unless I hear otherwise.

On Thu, Jun 6, 2024 at 5:25 PM Osamu Watanabe
<owatanab at es.takushoku-u.ac.jp> wrote:
>
> From: Osamu Watanabe <65328111+osamu620 at users.noreply.github.com>
>
> Fix http://trac.ffmpeg.org/ticket/10121
>
> Signed-off-by: Osamu Watanabe <owatanab at es.takushoku-u.ac.jp>
> ---
>  libavcodec/jpeg2000dec.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
> index d15502a527..091931b1ff 100644
> --- a/libavcodec/jpeg2000dec.c
> +++ b/libavcodec/jpeg2000dec.c
> @@ -1005,6 +1005,7 @@ static inline void select_header(Jpeg2000DecoderContext *s, const Jpeg2000Tile *
>  {
>      s->g = tile->tile_part[*tp_index].header_tpg;
>      if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
> +        av_log(s->avctx, AV_LOG_WARNING, "Packet header bytes in PPM marker segment is too short.\n");
>          if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
>              s->g = tile->tile_part[++(*tp_index)].tpg;
>          }
> @@ -1014,10 +1015,18 @@ static inline void select_header(Jpeg2000DecoderContext *s, const Jpeg2000Tile *
>  static inline void select_stream(Jpeg2000DecoderContext *s, const Jpeg2000Tile *tile,
>                                   int *tp_index, const Jpeg2000CodingStyle *codsty)
>  {
> +    int32_t is_endof_tp;
> +
>      s->g = tile->tile_part[*tp_index].tpg;
> -    if (bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8) {
> +    is_endof_tp = bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8;
> +    // Following while loop is necessary because a tilepart may include only SOD marker.
> +    // Such a tilepart has neither packet header nor compressed data.
> +    while (is_endof_tp) {
>          if (*tp_index < FF_ARRAY_ELEMS(tile->tile_part) - 1) {
>              s->g = tile->tile_part[++(*tp_index)].tpg;
> +            is_endof_tp = bytestream2_get_bytes_left(&s->g) == 0 && s->bit_index == 8;
> +        } else {
> +            is_endof_tp = 0;
>          }
>      }
>      if (codsty->csty & JPEG2000_CSTY_SOP) {
> --
> 2.34.1
>