From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCHv2] swscale: prevent undefined behaviour in the PUTRGBA macro
Date: Tue, 9 Jul 2024 14:44:14 +0200
Message-ID: <20240709124414.GW4991@pb2> (raw)
In-Reply-To: <20240708042517.5585-1-gseanmcg@gmail.com>
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On Mon, Jul 08, 2024 at 12:25:17AM -0400, Sean McGovern wrote:
> ---
> libswscale/yuv2rgb.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libswscale/yuv2rgb.c b/libswscale/yuv2rgb.c
> index 977eb3a7dd..ac0b811f61 100644
> --- a/libswscale/yuv2rgb.c
> +++ b/libswscale/yuv2rgb.c
> @@ -100,9 +100,9 @@ const int *sws_getCoefficients(int colorspace)
>
> #define PUTRGBA(dst, ysrc, asrc, i, abase) \
> Y = ysrc[2 * i]; \
> - dst[2 * i] = r[Y] + g[Y] + b[Y] + (asrc[2 * i] << abase); \
> + dst[2 * i] = r[Y] + g[Y] + b[Y] + ((int32_t)(asrc[2 * i]) << abase); \
> Y = ysrc[2 * i + 1]; \
> - dst[2 * i + 1] = r[Y] + g[Y] + b[Y] + (asrc[2 * i + 1] << abase);
> + dst[2 * i + 1] = r[Y] + g[Y] + b[Y] + ((int32_t)(asrc[2 * i + 1]) << abase);
can you explain what undefined behavior this does prevent and how ?
(in the commit message)
thx
[...]
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Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
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next prev parent reply other threads:[~2024-07-09 12:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-03 19:07 [FFmpeg-devel] [RFC] fix UB in fate-checkasm-sw_yuv2rgb Sean McGovern
2024-07-03 20:33 ` Rémi Denis-Courmont
2024-07-03 21:32 ` Sean McGovern
2024-07-08 4:25 ` [FFmpeg-devel] [PATCHv2] swscale: prevent undefined behaviour in the PUTRGBA macro Sean McGovern
2024-07-09 12:44 ` Michael Niedermayer [this message]
2024-07-09 18:34 ` [FFmpeg-devel] [PATCHv3] " Sean McGovern
2024-07-09 20:19 ` Leo Izen
2024-07-09 21:41 ` [FFmpeg-devel] [PATCHv4] " Sean McGovern
2024-07-10 16:09 ` Michael Niedermayer
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