[FFmpeg-devel] [PATCH 5/6] avformat/asfdec: Fix DoS due to lack of eof check

[Paul B Mahol]

On 8/25/17, Michael Niedermayer <michael at niedermayer.cc> wrote:
> From: ****** and *********(******) <tony.sh and wangchu.zhl at alibaba-inc.com>
>
> Fixes: loop.asf
>
> Found-by: Xiaohei and Wangchu from Alibaba Security Team
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/asfdec_f.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/asfdec_f.c b/libavformat/asfdec_f.c
> index be09a92bd1..00dd5ec41d 100644
> --- a/libavformat/asfdec_f.c
> +++ b/libavformat/asfdec_f.c
> @@ -749,13 +749,20 @@ static int asf_read_marker(AVFormatContext *s, int64_t
> size)
>      count = avio_rl32(pb);    // markers count
>      avio_rl16(pb);            // reserved 2 bytes
>      name_len = avio_rl16(pb); // name length
> -    for (i = 0; i < name_len; i++)
> +    for (i = 0; i < name_len; i++) {
> +        if (avio_feof(pb))
> +            return AVERROR_INVALIDDATA;
>          avio_r8(pb); // skip the name

This is very slow way to skip something.

> +    }
> +
>
>      for (i = 0; i < count; i++) {
>          int64_t pres_time;
>          int name_len;
>
> +        if (avio_feof(pb))
> +            return AVERROR_INVALIDDATA;
> +
>          avio_rl64(pb);             // offset, 8 bytes
>          pres_time = avio_rl64(pb); // presentation time
>          pres_time -= asf->hdr.preroll * 10000;
> --
> 2.14.1
>
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