[FFmpeg-devel] [PATCH] avcodec/fft_template: Fix multiple runtime error: signed integer overflow: -1943918714 - 1935113003 cannot be represented in type 'int'

[Michael Niedermayer]

On Fri, May 26, 2017 at 03:20:14PM +0100, Rostislav Pehlivanov wrote:
> On 26 May 2017 at 12:21, wm4 <nfxjfg at googlemail.com> wrote:
> 
> > On Thu, 25 May 2017 16:10:49 +0200
> > Michael Niedermayer <michael at niedermayer.cc> wrote:
> >
> > > Fixes: 1735/clusterfuzz-testcase-minimized-5350472347025408
> > >
> > > Found-by: continuous fuzzing process https://github.com/google/oss-
> > fuzz/tree/master/projects/ffmpeg
> > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > > ---
> > >  libavcodec/fft_template.c | 50 +++++++++++++++++++++++-------
> > -----------------
> > >  1 file changed, 25 insertions(+), 25 deletions(-)
> > >
> > > diff --git a/libavcodec/fft_template.c b/libavcodec/fft_template.c
> > > index 480557f49f..e3a37e5d69 100644
> > > --- a/libavcodec/fft_template.c
> > > +++ b/libavcodec/fft_template.c
> > > @@ -249,7 +249,7 @@ static void fft_calc_c(FFTContext *s, FFTComplex *z)
> > {
> > >
> > >      int nbits, i, n, num_transforms, offset, step;
> > >      int n4, n2, n34;
> > > -    FFTSample tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
> > > +    SUINT tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
> >
> > I want this SUINT thing gone, not have more of it.
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel at ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >
> 
> I agree, especially here.

> Overflows should be left to happen in transforms if the input is corrupt.

signed int overflow is not allowed in C, if that is what you meant.


> Codecs are designed such that transforms won't overflow unless corrupt data
> is fed. We allow for that to happen already (in the VP9 DCTs), so FFTs
> shouldn't be excluded.
> _______________________________________________
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> ffmpeg-devel at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel

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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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