[FFmpeg-devel] [PATCH 2/2] avcodec/h264: Check weight values to be within the specs limits.

[Michael Niedermayer]

On Wed, Mar 22, 2017 at 07:09:23PM +0100, Michael Niedermayer wrote:
> On Wed, Mar 22, 2017 at 09:06:09AM -0400, Ronald S. Bultje wrote:
> > Hi,
> > 
> > On Tue, Mar 21, 2017 at 9:59 PM, Michael Niedermayer <michael at niedermayer.cc
> > > wrote:
> > 
> > > @@ -59,6 +59,9 @@ int ff_h264_pred_weight_table(GetBitContext *gb, const
> > > SPS *sps,
> > >              if (luma_weight_flag) {
> > >                  pwt->luma_weight[i][list][0] = get_se_golomb(gb);
> > >                  pwt->luma_weight[i][list][1] = get_se_golomb(gb);
> > > +                if (   (int8_t)pwt->luma_weight[i][list][0] !=
> > > pwt->luma_weight[i][list][0]
> > > +                    || (int8_t)pwt->luma_weight[i][list][1] !=
> > > pwt->luma_weight[i][list][1])
> > > +                    goto error;
> > >
> > 
> > Can we please put || on the line before? h264* and a very limited subset of
> > other files in our codebase have always been an exception to the large
> > majority of the codebase and it's about time we fix that [1].
> 
> i find putting the operators in the first column more readable
> but if its preferred in the last, iam happy to change it.
> 
> 
> > 
> > It's interesting (I mean that in a positive way) how you use casting to
> > check for the range. It's a little obscure, but it's OK.
> 
> yes, it caused me to pause to but it was the simplest way i saw to do
> the check
> 
> 
> > 
> > +error:
> > > +    avpriv_request_sample(logctx, "Out of range weight\n");
> > > +    return AVERROR_INVALIDDATA;
> > 
> > 
> > Same comment as previously in other, but related, threads: unless there is
> > real, demonstrable evidence that this happens in real-world files, this is
> > fuzz/corruption only and shouldn't be accompanied by an explicit log
> > message. Just return AVERROR_INVALIDDATA directly and remove the goto/error
> > message.
> 
> If there is "real, demonstrable evidence that this happens in real-world
> files" then we would likely have a sample and not ask for one with
> avpriv_request_sample()
> 
> I think its very plausible that a encoder would use a weight that is
> outside the range. Printing something does make sense.

i will apply this with the label chaned to out_range_weight:
unless there are objections

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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