linux-kernel - Re: [PATCH] ep93xx: clock: Fix off by one in ep93xx_div_recalc

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Message-ID: <895c9d2f81023b8fa88209b244209202ce202af5.camel@gmail.com>
Date: Wed, 11 Sep 2024 09:52:28 +0200
From: Alexander Sverdlin <alexander.sverdlin@...il.com>
To: Dan Carpenter <dan.carpenter@...aro.org>, Nikita Shubin
	 <nikita.shubin@...uefel.me>
Cc: Hartley Sweeten <hsweeten@...ionengravers.com>, Russell King
	 <linux@...linux.org.uk>, Arnd Bergmann <arnd@...db.de>, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] ep93xx: clock: Fix off by one in
 ep93xx_div_recalc_rate()

Hi Dan!

On Wed, 2024-09-11 at 10:39 +0300, Dan Carpenter wrote:
> The psc->div[] array has psc->num_div elements.  These values come from
> when we call clk_hw_register_div().  It's adc_divisors and
> ARRAY_SIZE(adc_divisors)) and so on.  So this condition needs to be >=
> instead of > to prevent an out of bounds read.
> 
> Fixes: 9645ccc7bd7a ("ep93xx: clock: convert in-place to COMMON_CLK")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>

Acked-by: Alexander Sverdlin <alexander.sverdlin@...il.com>

> ---
>  arch/arm/mach-ep93xx/clock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-ep93xx/clock.c b/arch/arm/mach-ep93xx/clock.c
> index 85a496ddc619..e9f72a529b50 100644
> --- a/arch/arm/mach-ep93xx/clock.c
> +++ b/arch/arm/mach-ep93xx/clock.c
> @@ -359,7 +359,7 @@ static unsigned long ep93xx_div_recalc_rate(struct clk_hw *hw,
>  	u32 val = __raw_readl(psc->reg);
>  	u8 index = (val & psc->mask) >> psc->shift;
>  
> -	if (index > psc->num_div)
> +	if (index >= psc->num_div)
>  		return 0;
>  
>  	return DIV_ROUND_UP_ULL(parent_rate, psc->div[index]);

-- 
Alexander Sverdlin.