From: Andrew Jones <ajones@ventanamicro.com>
To: Erick Archer <erick.archer@gmx.com>
Cc: "Paul Walmsley" <paul.walmsley@sifive.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Conor Dooley" <conor.dooley@microchip.com>,
"Evan Green" <evan@rivosinc.com>,
"Clément Léger" <cleger@rivosinc.com>,
"Jisheng Zhang" <jszhang@kernel.org>,
"Charlie Jenkins" <charlie@rivosinc.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH] riscv: Use kcalloc() instead of kzalloc()
Date: Mon, 22 Jan 2024 09:52:33 +0100 [thread overview]
Message-ID: <20240122-7b031613b2ae1d7dfa1edfd7@orel> (raw)
In-Reply-To: <20240120135400.4710-1-erick.archer@gmx.com>
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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next prev parent reply other threads:[~2024-01-22 8:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-20 13:54 [PATCH] riscv: Use kcalloc() instead of kzalloc() Erick Archer
2024-01-22 7:58 ` Alexandre Ghiti
2024-01-22 8:52 ` Andrew Jones [this message]
2024-01-22 17:45 ` Gustavo A. R. Silva
2024-03-20 20:50 ` patchwork-bot+linux-riscv
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