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Message-ID: <b7cd5217-e7dc-4b57-aab2-bef1b78dca7d@embeddedor.com>
Date: Fri, 9 Feb 2024 12:40:36 -0600
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Subject: Re: [PATCH] irqchip/irq-bcm7038-l1: Prefer struct_size over open
 coded arithmetic
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To: Erick Archer <erick.archer@gmx.com>,
 Florian Fainelli <florian.fainelli@broadcom.com>,
 Thomas Gleixner <tglx@linutronix.de>,
 "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@broadcom.com>,
 linux-arm-kernel@lists.infradead.org, linux-hardening@vger.kernel.org
References: <20240209183128.10273-1-erick.archer@gmx.com>
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
In-Reply-To: <20240209183128.10273-1-erick.archer@gmx.com>
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On 2/9/24 12:31, Erick Archer wrote:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1].
> 
> As the cpu variable is a pointer to "struct bcm7038_l1_cpu" and this
> structure ends in a flexible array:
> 
> struct bcm7038_l1_cpu {
> 	void __iomem	*map_base;
> 	u32		mask_cache[];
> };
> 
> the preferred way in the kernel is to use the struct_size() helper to
> do the arithmetic instead of the argument "size + count * size" in the
> kzalloc() function.
> 
> This way, the code is more readable and more safer.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/162 [2]
> 
> Signed-off-by: Erick Archer <erick.archer@gmx.com>

LGTM:

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
-- 
Gustavo

> ---
>   drivers/irqchip/irq-bcm7038-l1.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/irqchip/irq-bcm7038-l1.c b/drivers/irqchip/irq-bcm7038-l1.c
> index 24ca1d656adc..36e71af054e9 100644
> --- a/drivers/irqchip/irq-bcm7038-l1.c
> +++ b/drivers/irqchip/irq-bcm7038-l1.c
> @@ -249,7 +249,7 @@ static int __init bcm7038_l1_init_one(struct device_node *dn,
>   		return -EINVAL;
>   	}
> 
> -	cpu = intc->cpus[idx] = kzalloc(sizeof(*cpu) + n_words * sizeof(u32),
> +	cpu = intc->cpus[idx] = kzalloc(struct_size(cpu, mask_cache, n_words),
>   					GFP_KERNEL);
>   	if (!cpu)
>   		return -ENOMEM;
> --
> 2.25.1
>