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From: "james qian wang (Arm Technology China)" <james.qian.wang@arm.com>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: David Airlie <airlied@linux.ie>,
	Liviu Dudau <Liviu.Dudau@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>, nd <nd@arm.com>
Subject: Re: drm/komeda: Fix potential integer overflow in komeda_crtc_update_clock_ratio
Date: Mon, 12 Aug 2019 10:18:11 +0000	[thread overview]
Message-ID: <20190812101805.GA3984@jamwan02-TSP300> (raw)
In-Reply-To: <20190812000801.GA29204@embeddedor>

On Sun, Aug 11, 2019 at 07:08:01PM -0500, Gustavo A. R. Silva wrote:
> Add suffix ULL to constant 1000 in order to avoid a potential integer
> overflow and give the compiler complete information about the proper
> arithmetic to use. Notice that this constant is being used in a context
> that expects an expression of type u64, but it's currently evaluated
> using 32-bit arithmetic.
> 
> Addresses-Coverity-ID: 1485796 ("Unintentional integer overflow")
> Fixes: ed22c6d9304d ("drm/komeda: Use drm_display_mode "crtc_" prefixed hardware timings")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
>  drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> index fa9a4593bb37..624d257da20f 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> @@ -27,7 +27,7 @@ static void komeda_crtc_update_clock_ratio(struct komeda_crtc_state *kcrtc_st)
>  		return;
>  	}
>  
> -	pxlclk = kcrtc_st->base.adjusted_mode.crtc_clock * 1000;
> +	pxlclk = kcrtc_st->base.adjusted_mode.crtc_clock * 1000ULL;
>  	aclk = komeda_crtc_get_aclk(kcrtc_st);
>  
>  	kcrtc_st->clock_ratio = div64_u64(aclk << 32, pxlclk);

Thank you for the patch.

Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
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WARNING: multiple messages have this Message-ID (diff)
From: "james qian wang (Arm Technology China)" <james.qian.wang@arm.com>
To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Cc: Liviu Dudau <Liviu.Dudau@arm.com>,
	Brian Starkey <Brian.Starkey@arm.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>, nd <nd@arm.com>
Subject: Re: drm/komeda: Fix potential integer overflow in komeda_crtc_update_clock_ratio
Date: Mon, 12 Aug 2019 10:18:11 +0000	[thread overview]
Message-ID: <20190812101805.GA3984@jamwan02-TSP300> (raw)
In-Reply-To: <20190812000801.GA29204@embeddedor>

On Sun, Aug 11, 2019 at 07:08:01PM -0500, Gustavo A. R. Silva wrote:
> Add suffix ULL to constant 1000 in order to avoid a potential integer
> overflow and give the compiler complete information about the proper
> arithmetic to use. Notice that this constant is being used in a context
> that expects an expression of type u64, but it's currently evaluated
> using 32-bit arithmetic.
> 
> Addresses-Coverity-ID: 1485796 ("Unintentional integer overflow")
> Fixes: ed22c6d9304d ("drm/komeda: Use drm_display_mode "crtc_" prefixed hardware timings")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
>  drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> index fa9a4593bb37..624d257da20f 100644
> --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c
> @@ -27,7 +27,7 @@ static void komeda_crtc_update_clock_ratio(struct komeda_crtc_state *kcrtc_st)
>  		return;
>  	}
>  
> -	pxlclk = kcrtc_st->base.adjusted_mode.crtc_clock * 1000;
> +	pxlclk = kcrtc_st->base.adjusted_mode.crtc_clock * 1000ULL;
>  	aclk = komeda_crtc_get_aclk(kcrtc_st);
>  
>  	kcrtc_st->clock_ratio = div64_u64(aclk << 32, pxlclk);

Thank you for the patch.

Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>

  reply	other threads:[~2019-08-12 10:18 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-12  0:08 [PATCH] drm/komeda: Fix potential integer overflow in komeda_crtc_update_clock_ratio Gustavo A. R. Silva
2019-08-12 10:18 ` james qian wang (Arm Technology China) [this message]
2019-08-12 10:18   ` james qian wang (Arm Technology China)

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