[FFmpeg-devel] [PATCH] mpeg12enc: fix wrong size when copying A53_CC side-data into output

[FFmpeg-devel] [PATCH] mpeg12enc: fix wrong size when copying A53_CC side-data into output

[Jacob Lifshay]

Fixes: https://trac.ffmpeg.org/ticket/11591

Signed-off-by: Jacob Lifshay <programmerjake@gmail.com>
---
 libavcodec/mpeg12enc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/mpeg12enc.c b/libavcodec/mpeg12enc.c
index 8364368fde..e48437eb8a 100644
--- a/libavcodec/mpeg12enc.c
+++ b/libavcodec/mpeg12enc.c
@@ -472,7 +472,7 @@ static int mpeg1_encode_picture_header(MPVMainEncContext *const m)
                     (side_data->size / 3 & A53_MAX_CC_COUNT) | 0x40); // flags, cc_count
                 put_bits(&s->pb, 8, 0xff);                  // em_data
 
-                ff_copy_bits(&s->pb, side_data->data, side_data->size);
+                ff_copy_bits(&s->pb, side_data->data, side_data->size * 8);
 
                 put_bits(&s->pb, 8, 0xff);                  // marker_bits
             } else {
-- 
2.39.5

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Re: [FFmpeg-devel] [PATCH] mpeg12enc: fix wrong size when copying A53_CC side-data into output

[Andreas Rheinhardt]

Jacob Lifshay:
> Fixes: https://trac.ffmpeg.org/ticket/11591
> 
> Signed-off-by: Jacob Lifshay <programmerjake@gmail.com>
> ---
>  libavcodec/mpeg12enc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/mpeg12enc.c b/libavcodec/mpeg12enc.c
> index 8364368fde..e48437eb8a 100644
> --- a/libavcodec/mpeg12enc.c
> +++ b/libavcodec/mpeg12enc.c
> @@ -472,7 +472,7 @@ static int mpeg1_encode_picture_header(MPVMainEncContext *const m)
>                      (side_data->size / 3 & A53_MAX_CC_COUNT) | 0x40); // flags, cc_count
>                  put_bits(&s->pb, 8, 0xff);                  // em_data
>  
> -                ff_copy_bits(&s->pb, side_data->data, side_data->size);
> +                ff_copy_bits(&s->pb, side_data->data, side_data->size * 8);
>  
>                  put_bits(&s->pb, 8, 0xff);                  // marker_bits
>              } else {

Thanks for this patch (and for the bug report; and sorry for causing you
trouble). Your patch was also my first attempt to fix this, but
unfortunately ff_copy_bits() may overread, yet the side data buffer need
not be padded, so my patch simply reverts the ff_copy_bits().

- Andreas

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Re: [FFmpeg-devel] [PATCH] mpeg12enc: fix wrong size when copying A53_CC side-data into output

[Jacob Lifshay]

On Thu, May 15, 2025 at 6:15 PM Andreas Rheinhardt
<andreas.rheinhardt@outlook.com> wrote:
> Thanks for this patch (and for the bug report; and sorry for causing you
> trouble). Your patch was also my first attempt to fix this, but
> unfortunately ff_copy_bits() may overread, yet the side data buffer need
> not be padded, so my patch simply reverts the ff_copy_bits().

ok, sounds good. Thanks for the quick fix!

Jacob
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