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

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Message-ID: <048fc58d-abbb-4696-9ed0-f5a0fadce740@ghiti.fr>
Date: Mon, 22 Jan 2024 08:58:58 +0100
From: Alexandre Ghiti <alex@...ti.fr>
To: Erick Archer <erick.archer@....com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Conor Dooley <conor.dooley@...rochip.com>,
 Andrew Jones <ajones@...tanamicro.com>, Evan Green <evan@...osinc.com>,
 Clément Léger <cleger@...osinc.com>,
 Jisheng Zhang <jszhang@...nel.org>, Charlie Jenkins <charlie@...osinc.com>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH] riscv: Use kcalloc() instead of kzalloc()

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@....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@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

You can add:

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

Thanks,

Alex

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