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

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

[Erick Archer]

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@gmx.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

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

[Kees Cook]

On Sun, Feb 11, 2024 at 06:51:43PM +0100, Erick Archer wrote:
> 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@gmx.com>

Looks reasonable.

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

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

[Gustavo A. R. Silva]

On 2/11/24 11:51, Erick Archer wrote:
> 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@gmx.com>

LGTM:

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks!
-- 
Gustavo

> ---
>   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
> 
> 

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

[Baolu Lu]

On 2/12/24 1:51 AM, Erick Archer wrote:
> 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@gmx.com>
> ---
>   drivers/iommu/intel/perf.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

I have queued this patch for v6.9.

Best regards,
baolu