linux-kernel - [PATCH] iommu/vt-d: Use kcalloc() instead of kzalloc()

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Date: Sun, 11 Feb 2024 18:51:43 +0100
From: Erick Archer <erick.archer@....com>
To: David Woodhouse <dwmw2@...radead.org>,
	Lu Baolu <baolu.lu@...ux.intel.com>,
	Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	Kees Cook <keescook@...omium.org>
Cc: Erick Archer <erick.archer@....com>,
	iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: [PATCH] iommu/vt-d: Use kcalloc() instead of kzalloc()

This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1].

Here the multiplication is obviously safe because DMAR_LATENCY_NUM
is the number of latency types defined in the "latency_type" enum.

enum latency_type {
	DMAR_LATENCY_INV_IOTLB = 0,
	DMAR_LATENCY_INV_DEVTLB,
	DMAR_LATENCY_INV_IEC,
	DMAR_LATENCY_PRQ,
	DMAR_LATENCY_NUM
};

However, using kcalloc() is more appropriate [2] and improves
readability. This patch has no effect on runtime behavior.

Link: https://github.com/KSPP/linux/issues/162 [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [2]
Signed-off-by: Erick Archer <erick.archer@....com>
---
 drivers/iommu/intel/perf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/perf.c b/drivers/iommu/intel/perf.c
index 94ee70ac38e3..adc4de6bbd88 100644
--- a/drivers/iommu/intel/perf.c
+++ b/drivers/iommu/intel/perf.c
@@ -33,7 +33,7 @@ int dmar_latency_enable(struct intel_iommu *iommu, enum latency_type type)

 	spin_lock_irqsave(&latency_lock, flags);
 	if (!iommu->perf_statistic) {
-		iommu->perf_statistic = kzalloc(sizeof(*lstat) * DMAR_LATENCY_NUM,
+		iommu->perf_statistic = kcalloc(DMAR_LATENCY_NUM, sizeof(*lstat),
 						GFP_ATOMIC);
 		if (!iommu->perf_statistic) {
 			ret = -ENOMEM;
--
2.25.1