[FFmpeg-devel] [PATCH 6/6] avformat/hls: Fix DoS due to infinite loop

[Michael Niedermayer]

On Fri, Aug 25, 2017 at 10:08:23AM +0200, wm4 wrote:
> On Fri, 25 Aug 2017 01:15:32 +0200
> Michael Niedermayer <michael at niedermayer.cc> wrote:
> 
> > Fixes: loop.m3u
> > 
> > The max iteration count of 10000 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 | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/libavformat/hls.c b/libavformat/hls.c
> > index 01731bd36b..26f4ebd965 100644
> > --- a/libavformat/hls.c
> > +++ b/libavformat/hls.c
> > @@ -1263,6 +1263,7 @@ 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 +1295,9 @@ restart:
> >          reload_interval = default_reload_interval(v);
> >  
> >  reload:
> > +        reload_count++;
> > +        if (reload_count > 10000)
> > +            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) {
> 
> Why 1000?

Please read the commit message at the top of the mail you reply to,
that is explained in it


> 
> This patch is unnecessary. The interrupt callback can break out of this
> loop anyway on user request. Or is this patch again intended for
> transcode servers with hilariously insecure amateurish configuration,
> like most of these patches seem to be?

Do you object to this issue being fixed ?
In which case i will of course respect your veto and leave the issue
open.
Otherwise i will here note that i disagree with your oppinion.

And will resubmit a patch with the changes requested by the maintainer

Thanks

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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