linux-hardening - Re: [PATCH] irqchip/bcm-6345-l1: Prefer struct

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Date: Fri, 9 Feb 2024 12:38:18 -0600
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Erick Archer <erick.archer@....com>,
 Florian Fainelli <florian.fainelli@...adcom.com>,
 Thomas Gleixner <tglx@...utronix.de>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] irqchip/bcm-6345-l1: Prefer struct_size over open coded
 arithmetic



On 2/9/24 12:16, 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 bcm6345_l1_cpu" and this
> structure ends in a flexible array:
> 
> struct bcm6345_l1_cpu {
> 	[...]
> 	u32	enable_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@....com>

LGTM:

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

Thanks
-- 
Gustavo

> ---
>   drivers/irqchip/irq-bcm6345-l1.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/irqchip/irq-bcm6345-l1.c b/drivers/irqchip/irq-bcm6345-l1.c
> index 9745a119d0e6..eb02d203c963 100644
> --- a/drivers/irqchip/irq-bcm6345-l1.c
> +++ b/drivers/irqchip/irq-bcm6345-l1.c
> @@ -242,7 +242,7 @@ static int __init bcm6345_l1_init_one(struct device_node *dn,
>   	else if (intc->n_words != n_words)
>   		return -EINVAL;
> 
> -	cpu = intc->cpus[idx] = kzalloc(sizeof(*cpu) + n_words * sizeof(u32),
> +	cpu = intc->cpus[idx] = kzalloc(struct_size(cpu, enable_cache, n_words),
>   					GFP_KERNEL);
>   	if (!cpu)
>   		return -ENOMEM;
> --
> 2.25.1
> 
>