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>
---
 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

On 2/9/2024 10:31 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 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>

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

On Fri, Feb 09, 2024 at 07:31:28PM +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 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>

Yeah, looks right to me.

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

-- 
Kees Cook

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
>

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     e955a71f83598a347eb45af5576e7eb6cb5bf285
Gitweb:        https://git.kernel.org/tip/e955a71f83598a347eb45af5576e7eb6cb5bf285
Author:        Erick Archer <erick.archer@gmx.com>
AuthorDate:    Fri, 09 Feb 2024 19:31:28 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 13 Feb 2024 10:53:15 +01:00

irqchip/irq-bcm7038-l1: Prefer struct_size over open coded arithmetic

This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows.

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.

Signed-off-by: Erick Archer <erick.archer@gmx.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20240209183128.10273-1-erick.archer@gmx.com
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]
---
 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 24ca1d6..36e71af 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;