[FFmpeg-devel] [PATCH] avformat/hls: Fix DoS due to infinite loop

[Steven Liu]

2017-08-25 18:14 GMT+08:00 Michael Niedermayer <michael at niedermayer.cc>:
> Fixes: loop.m3u
>
> The default max iteration count of 1000 is arbitrary and ideas for a better solution are welcome
>
> Found-by: Xiaohei and Wangchu from Alibaba Security Team
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/hls.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/libavformat/hls.c b/libavformat/hls.c
> index 01731bd36b..0995345bbf 100644
> --- a/libavformat/hls.c
> +++ b/libavformat/hls.c
> @@ -205,6 +205,7 @@ typedef struct HLSContext {
>      AVDictionary *avio_opts;
>      int strict_std_compliance;
>      char *allowed_extensions;
> +    int max_reload;
>  } HLSContext;
>
>  static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
> @@ -1263,6 +1264,7 @@ static int read_data(void *opaque, uint8_t *buf, int buf_size)
>      HLSContext *c = v->parent->priv_data;
>      int ret, i;
>      int just_opened = 0;
> +    int reload_count = 0;
>
>  restart:
>      if (!v->needed)
> @@ -1294,6 +1296,9 @@ restart:
>          reload_interval = default_reload_interval(v);
>
>  reload:
> +        reload_count++;
> +        if (reload_count > c->max_reload)
> +            return AVERROR_EOF;
>          if (!v->finished &&
>              av_gettime_relative() - v->last_load_time >= reload_interval) {
>              if ((ret = parse_playlist(c, v->url, v, NULL)) < 0) {
> @@ -2150,6 +2155,8 @@ static const AVOption hls_options[] = {
>          OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
>          {.str = "3gp,aac,avi,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
>          INT_MIN, INT_MAX, FLAGS},
> +    {"max_reload", "Maximum number of times a insufficient list is attempted to be reloaded",
> +        OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, FLAGS},
>      {NULL}
>  };
>
> --
> 2.14.1
>
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should be ok,  and the demuxer option need a document.