Re: [FFmpeg-devel] [PATCH 04/17] avcodec/dxva2: initialize hr in ff_dxva2_common_end_frame()

[Michael Niedermayer <michael@niedermayer.cc>]

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On Sun, Jun 02, 2024 at 09:10:33PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > Fixes: CID1591924 Uninitialized scalar variable
> > Fixes: CID1591938 Uninitialized scalar variable
> > 
> > Sponsored-by: Sovereign Tech Fund
> > Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> > ---
> >  libavcodec/dxva2.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libavcodec/dxva2.c b/libavcodec/dxva2.c
> > index 1a33c8bbac7..22ecd5acafe 100644
> > --- a/libavcodec/dxva2.c
> > +++ b/libavcodec/dxva2.c
> > @@ -906,7 +906,7 @@ int ff_dxva2_common_end_frame(AVCodecContext *avctx, AVFrame *frame,
> >  #endif
> >      DECODER_BUFFER_DESC             *buffer = NULL, *buffer_slice = NULL;
> >      int result, runs = 0;
> > -    HRESULT hr;
> > +    HRESULT hr = -1;
> >      unsigned type;
> >      FFDXVASharedContext *sctx = DXVA_SHARED_CONTEXT(avctx);
> >  
> 
> It seems to me that this (and other patches in this set) is not a real
> fix of a bug. These functions are called either with a D3D11 pix fmt or
> with AV_PIX_FMT_DXVA2_VLD, so these variables are initialized before
> their use.

If they are called with another pixel format then its exploitable
maybe that cannot happen currently

But if or if not. Initializing these variables makes the code simply
more robust and also if it happens a NULL is easier to debug than
uninitialized variables. The assumtions that need to be true for
them to be initialized are not entirely trivial.

ill drop the patches from what i wanted to apply currently but i still
think they should be applied.
I can change the commit message if you can suggest something else ?

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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