Re: [FFmpeg-devel] [PATCH 3/4] avformat/img2dec: ensure input padding is zeroed

From: Paul B Mahol <onemda@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Cc: "Kacper Michajłow" <kasper93@gmail.com>
Subject: Re: [FFmpeg-devel] [PATCH 3/4] avformat/img2dec: ensure input padding is zeroed
Date: Thu, 27 Jun 2024 08:59:15 +0200
Message-ID: <CAPYw7P5wC5ZbtjvdzcEDj+EhMY6Ww0-O=4fThAJh1um-s=6oaA@mail.gmail.com> (raw)
In-Reply-To: <20240627004037.1336-3-kasper93@gmail.com>

On Thu, Jun 27, 2024 at 3:57 AM Kacper Michajłow <kasper93@gmail.com> wrote:

> Fixes use of uninitialized value, reported by MSAN. Specifically in
> jpegxl parser.
>
> Found by OSS-Fuzz.
>
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
>  libavformat/img2dec.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/libavformat/img2dec.c b/libavformat/img2dec.c
> index ba52353074..c667d8574c 100644
> --- a/libavformat/img2dec.c
> +++ b/libavformat/img2dec.c
> @@ -549,6 +549,8 @@ int ff_img_read_packet(AVFormatContext *s1, AVPacket
> *pkt)
>          }
>      }
>
> +    memset(pkt->data + pkt->size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
> +
>      if (ret[0] <= 0 || ret[1] < 0 || ret[2] < 0) {
>          if (ret[0] < 0) {
>              res = ret[0];
> --
> 2.43.0
>
>
Isn't this done generically already?
Otherwise this fix is just fixing one single case of numerous others not
covered.

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