linux-hardening - Re: [PATCH] perf/x86/amd/uncore: Use kcalloc*() instead of kzalloc*()

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Date: Tue, 16 Jan 2024 10:30:53 -0600
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Erick Archer <erick.archer@....com>, Peter Zijlstra
 <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>, x86@...nel.org
Cc: Mark Rutland <mark.rutland@....com>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
 Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
 Adrian Hunter <adrian.hunter@...el.com>, "H. Peter Anvin" <hpa@...or.com>,
 linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH] perf/x86/amd/uncore: Use kcalloc*() instead of kzalloc*()

On 1/16/24 06:58, 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
> size * count in the kzalloc*() function.
> 
> [1] https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> 
> Link: https://github.com/KSPP/linux/issues/162
> Signed-off-by: Erick Archer <erick.archer@....com>

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

Thanks!
-- 
Gustavo

> ---
>   arch/x86/events/amd/uncore.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
> index 5bf03c575812..9073eb0613cf 100644
> --- a/arch/x86/events/amd/uncore.c
> +++ b/arch/x86/events/amd/uncore.c
> @@ -479,8 +479,8 @@ static int amd_uncore_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
>   				goto fail;
> 
>   			curr->cpu = cpu;
> -			curr->events = kzalloc_node(sizeof(*curr->events) *
> -						    pmu->num_counters,
> +			curr->events = kcalloc_node(pmu->num_counters,
> +						    sizeof(*curr->events),
>   						    GFP_KERNEL, node);
>   			if (!curr->events) {
>   				kfree(curr);
> @@ -928,7 +928,7 @@ int amd_uncore_umc_ctx_init(struct amd_uncore *uncore, unsigned int cpu)
>   		uncore->num_pmus += group_num_pmus[gid];
>   	}
> 
> -	uncore->pmus = kzalloc(sizeof(*uncore->pmus) * uncore->num_pmus,
> +	uncore->pmus = kcalloc(uncore->num_pmus, sizeof(*uncore->pmus),
>   			       GFP_KERNEL);
>   	if (!uncore->pmus) {
>   		uncore->num_pmus = 0;
> --
> 2.25.1
> 
>