[tip: irq/core] irqchip/irq-bcm7038-l1: Prefer struct_size over open coded arithmetic

[tip-bot2 for Erick Archer]

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@xxxxxxx>
AuthorDate:    Fri, 09 Feb 2024 19:31:28 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240209183128.10273-1-erick.archer@xxxxxxx
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;