[FFmpeg-devel] [PATCH 3/7] vorbis: Reorder conditions to avoid possible overread

[Rostislav Pehlivanov]

On 17 October 2017 at 23:11, Mark Thompson <sw at jkqxz.net> wrote:

> This can trigger a single-byte overread if the codebook has the maximum
> number of entries.
>
> Fixes #6743.
> ---
>  libavcodec/vorbis.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libavcodec/vorbis.c b/libavcodec/vorbis.c
> index 399020eec5..ce23b947f0 100644
> --- a/libavcodec/vorbis.c
> +++ b/libavcodec/vorbis.c
> @@ -58,7 +58,7 @@ int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes,
> unsigned num)
>      uint32_t exit_at_level[33] = { 404 };
>      unsigned i, j, p, code;
>
> -    for (p = 0; (bits[p] == 0) && (p < num); ++p)
> +    for (p = 0; (p < num) && (bits[p] == 0); ++p)
>          ;
>      if (p == num)
>          return 0;
> @@ -71,7 +71,7 @@ int ff_vorbis_len2vlc(uint8_t *bits, uint32_t *codes,
> unsigned num)
>
>      ++p;
>
> -    for (i = p; (bits[i] == 0) && (i < num); ++i)
> +    for (i = p; (i < num) && (bits[i] == 0); ++i)
>          ;
>      if (i == num)
>          return 0;
> --
> 2.11.0
>
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>

LGTM
I'll get around to merging the psy stuff one of these days