irqchip/bcm-6345-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 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 safer.

Signed-off-by: Erick Archer <erick.archer@gmx.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20240209181600.9472-1-erick.archer@gmx.com
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
Link: https://github.com/KSPP/linux/issues/162

diff --git a/drivers/irqchip/irq-bcm6345-l1.c b/drivers/irqchip/irq-bcm6345-l1.c
index 9745a119d0e66131524c5999458d42eda2c4b570..eb02d203c9634fb649a27ce03c6a9c00785b60e0 100644 (file)
--- 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;