Re: [FFmpeg-devel] [PATCH 2/5] avcodec/cdgraphics: avoid signed overflow in alpha

[Michael Niedermayer <michael@niedermayer.cc>]

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On Thu, Dec 23, 2021 at 10:45:47PM +0100, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: left shift of 255 by 24 places cannot be represented in type 'int'
> > Fixes: 42766/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_CDGRAPHICS_fuzzer-5142826105569280
> > 
> > Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/cdgraphics.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/cdgraphics.c b/libavcodec/cdgraphics.c
> > index 06f83920943..f54ce5a05c0 100644
> > --- a/libavcodec/cdgraphics.c
> > +++ b/libavcodec/cdgraphics.c
> > @@ -122,7 +122,7 @@ static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
> >          r = ((color >> 8) & 0x000F) * 17;
> >          g = ((color >> 4) & 0x000F) * 17;
> >          b = ((color     ) & 0x000F) * 17;
> > -        palette[i + array_offset] = cc->alpha[i + array_offset] << 24 | r << 16 | g << 8 | b;
> > +        palette[i + array_offset] = (unsigned)cc->alpha[i + array_offset] << 24 | r << 16 | g << 8 | b;
> >      }
> >      cc->frame->palette_has_changed = 1;
> >  }
> > 
> 
> LGTM. Although I'd prefer uint32_t here, as this is exactly what is
> needed and it fits the type of palette.

will apply32_t

thx

[...]

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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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