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Message-ID: <048fc58d-abbb-4696-9ed0-f5a0fadce740@ghiti.fr>
Date: Mon, 22 Jan 2024 08:58:58 +0100
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Subject: Re: [PATCH] riscv: Use kcalloc() instead of kzalloc()
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To: Erick Archer <erick.archer@gmx.com>,
 Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt
 <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>,
 Conor Dooley <conor.dooley@microchip.com>,
 Andrew Jones <ajones@ventanamicro.com>, Evan Green <evan@rivosinc.com>,
 =?UTF-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= <cleger@rivosinc.com>,
 Jisheng Zhang <jszhang@kernel.org>, Charlie Jenkins <charlie@rivosinc.com>,
 "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
 linux-hardening@vger.kernel.org
References: <20240120135400.4710-1-erick.archer@gmx.com>
From: Alexandre Ghiti <alex@ghiti.fr>
In-Reply-To: <20240120135400.4710-1-erick.archer@gmx.com>
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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