[PATCH] irqchip/bcm-6345-l1: Prefer struct_size over open coded arithmetic

[PATCH] irqchip/bcm-6345-l1: Prefer struct_size over open coded arithmetic

[Erick Archer]

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@gmx.com>
---
 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

Re: [PATCH] irqchip/bcm-6345-l1: Prefer struct_size over open coded arithmetic

[Gustavo A. R. Silva]

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@gmx.com>

LGTM:

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

Re: [PATCH] irqchip/bcm-6345-l1: Prefer struct_size over open coded arithmetic

[Kees Cook]

On Fri, Feb 09, 2024 at 07:16:00PM +0100, 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@gmx.com>

Thanks!

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH] irqchip/bcm-6345-l1: Prefer struct_size over open coded arithmetic

[Florian Fainelli]

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On 2/9/2024 10:16 AM, 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@gmx.com>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian

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