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
Link: https://github.com/KSPP/linux/issues/162

diff --git a/drivers/irqchip/irq-bcm7038-l1.c b/drivers/irqchip/irq-bcm7038-l1.c
index 24ca1d656adc5ef6680b4653417f18c8e7ef09d3..36e71af054e9794248e4ea8a2b2efb77c6895e14 100644 (file)
--- 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;