Re: [FFmpeg-devel] [PATCH] vp9: don't overread by 4 pixels in ff_vp9_avg4_mmxext().

From: "Ronald S. Bultje" <rsbultje@gmail.com>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH] vp9: don't overread by 4 pixels in ff_vp9_avg4_mmxext().
Date: Wed, 1 Jun 2022 14:32:37 -0400
Message-ID: <CAEEMt2=VAxiAW9U205ow1RGqpAu3LGzo0FHVNiWY73AOU9q0mg@mail.gmail.com> (raw)
In-Reply-To: <20220531132130.60467-1-rsbultje@gmail.com>

Hi,

On Tue, May 31, 2022 at 9:21 AM Ronald S. Bultje <rsbultje@gmail.com> wrote:

> If the block is at the end of the allocated buffer and there is no
> padding, this will over-read, which may cause crashes. Reported by
> Firefox.
> ---
>  libavcodec/x86/vp9mc.asm | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/libavcodec/x86/vp9mc.asm b/libavcodec/x86/vp9mc.asm
> index f64161b2c2..efc4cfbef1 100644
> --- a/libavcodec/x86/vp9mc.asm
> +++ b/libavcodec/x86/vp9mc.asm
> @@ -604,7 +604,12 @@ cglobal vp9_%1%2 %+ %%szsuf, 5, 5, %8, dst, dstride,
> src, sstride, h
>      %%pavg      m0, [dstq]
>      %%pavg      m1, [dstq+d%3]
>      %%pavg      m2, [dstq+d%4]
> +%if %2 == 4
> +    %%srcfn     m4, [dstq+d%5]
> +    %%pavg      m3, m4
> +%else
>      %%pavg      m3, [dstq+d%5]
> +%endif
>  %if %2/mmsize == 8
>      %%pavg      m4, [dstq+mmsize*4]
>      %%pavg      m5, [dstq+mmsize*5]
> --
> 2.34.1
>

Merged.

Ronald
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