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From: Erick Archer <erick.archer@gmx.com>
To: Florian Fainelli <florian.fainelli@broadcom.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Erick Archer <erick.archer@gmx.com>,
	linux-mips@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>,
	linux-hardening@vger.kernel.org
Subject: [PATCH] irqchip/bcm-6345-l1: Prefer struct_size over open coded arithmetic
Date: Fri,  9 Feb 2024 19:16:00 +0100
Message-Id: <20240209181600.9472-1-erick.archer@gmx.com>
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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>
=2D--
 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-bcm634=
5-l1.c
index 9745a119d0e6..eb02d203c963 100644
=2D-- 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_no=
de *dn,
 	else if (intc->n_words !=3D n_words)
 		return -EINVAL;

-	cpu =3D intc->cpus[idx] =3D kzalloc(sizeof(*cpu) + n_words * sizeof(u32)=
,
+	cpu =3D intc->cpus[idx] =3D kzalloc(struct_size(cpu, enable_cache, n_wor=
ds),
 					GFP_KERNEL);
 	if (!cpu)
 		return -ENOMEM;
=2D-
2.25.1