[PATCH] riscv: Use kcalloc() instead of kzalloc()

[PATCH] riscv: Use kcalloc() instead of kzalloc()

[Erick Archer]

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, use the purpose specific kcalloc() function instead of the argument
count * size in the kzalloc() function.

Also, it is preferred to use sizeof(*pointer) instead of sizeof(type)
due to the type of the variable can change and one needs not change the
former (unlike the latter).

Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Link: https://github.com/KSPP/linux/issues/162
Signed-off-by: Erick Archer <erick.archer@gmx.com>
---
 arch/riscv/kernel/cpufeature.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 89920f84d0a3..549a76e34c4e 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -901,8 +901,7 @@ static int check_unaligned_access_all_cpus(void)
 {
 	unsigned int cpu;
 	unsigned int cpu_count = num_possible_cpus();
-	struct page **bufs = kzalloc(cpu_count * sizeof(struct page *),
-				     GFP_KERNEL);
+	struct page **bufs = kcalloc(cpu_count, sizeof(*bufs), GFP_KERNEL);

 	if (!bufs) {
 		pr_warn("Allocation failure, not measuring misaligned performance\n");
--
2.25.1


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Re: [PATCH] riscv: Use kcalloc() instead of kzalloc()

[Alexandre Ghiti]

Hi Erick,

On 20/01/2024 14:54, Erick Archer wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
>
> So, use the purpose specific kcalloc() function instead of the argument
> count * size in the kzalloc() function.
>
> Also, it is preferred to use sizeof(*pointer) instead of sizeof(type)
> due to the type of the variable can change and one needs not change the
> former (unlike the latter).
>
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/162
> Signed-off-by: Erick Archer <erick.archer@gmx.com>
> ---
>   arch/riscv/kernel/cpufeature.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 89920f84d0a3..549a76e34c4e 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -901,8 +901,7 @@ static int check_unaligned_access_all_cpus(void)
>   {
>   	unsigned int cpu;
>   	unsigned int cpu_count = num_possible_cpus();
> -	struct page **bufs = kzalloc(cpu_count * sizeof(struct page *),
> -				     GFP_KERNEL);
> +	struct page **bufs = kcalloc(cpu_count, sizeof(*bufs), GFP_KERNEL);
>
>   	if (!bufs) {
>   		pr_warn("Allocation failure, not measuring misaligned performance\n");
> --
> 2.25.1
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv


You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex


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Re: [PATCH] riscv: Use kcalloc() instead of kzalloc()

[Andrew Jones]

On Sat, Jan 20, 2024 at 02:54:00PM +0100, Erick Archer wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
> 
> So, use the purpose specific kcalloc() function instead of the argument
> count * size in the kzalloc() function.
> 
> Also, it is preferred to use sizeof(*pointer) instead of sizeof(type)
> due to the type of the variable can change and one needs not change the
> former (unlike the latter).
> 
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/162
> Signed-off-by: Erick Archer <erick.archer@gmx.com>
> ---
>  arch/riscv/kernel/cpufeature.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 89920f84d0a3..549a76e34c4e 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -901,8 +901,7 @@ static int check_unaligned_access_all_cpus(void)
>  {
>  	unsigned int cpu;
>  	unsigned int cpu_count = num_possible_cpus();
> -	struct page **bufs = kzalloc(cpu_count * sizeof(struct page *),
> -				     GFP_KERNEL);
> +	struct page **bufs = kcalloc(cpu_count, sizeof(*bufs), GFP_KERNEL);
> 
>  	if (!bufs) {
>  		pr_warn("Allocation failure, not measuring misaligned performance\n");
> --
> 2.25.1
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

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Re: [PATCH] riscv: Use kcalloc() instead of kzalloc()

[Gustavo A. R. Silva]

On 1/20/24 07:54, Erick Archer wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
> 
> So, use the purpose specific kcalloc() function instead of the argument
> count * size in the kzalloc() function.
> 
> Also, it is preferred to use sizeof(*pointer) instead of sizeof(type)
> due to the type of the variable can change and one needs not change the
> former (unlike the latter).
> 
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Link: https://github.com/KSPP/linux/issues/162
> Signed-off-by: Erick Archer <erick.archer@gmx.com>

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

Thanks!
-- 
Gustavo

> ---
>   arch/riscv/kernel/cpufeature.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 89920f84d0a3..549a76e34c4e 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -901,8 +901,7 @@ static int check_unaligned_access_all_cpus(void)
>   {
>   	unsigned int cpu;
>   	unsigned int cpu_count = num_possible_cpus();
> -	struct page **bufs = kzalloc(cpu_count * sizeof(struct page *),
> -				     GFP_KERNEL);
> +	struct page **bufs = kcalloc(cpu_count, sizeof(*bufs), GFP_KERNEL);
> 
>   	if (!bufs) {
>   		pr_warn("Allocation failure, not measuring misaligned performance\n");
> --
> 2.25.1
> 
> 

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Re: [PATCH] riscv: Use kcalloc() instead of kzalloc()

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Sat, 20 Jan 2024 14:54:00 +0100 you wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
> 
> [...]

Here is the summary with links:
  - riscv: Use kcalloc() instead of kzalloc()
    https://git.kernel.org/riscv/c/28e4748e5e3d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



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