linux-kernel - Re: [PATCH -next v2] x86/events:Use struct

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Thu, 19 May 2022 09:52:20 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Lin Yujun <linyujun809@...wei.com>
Cc:     mingo@...hat.com, acme@...nel.org, mark.rutland@....com,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        namhyung@...nel.org, tglx@...utronix.de, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        gustavoars@...nel.org, johnny.chenyi@...wei.com,
        chenjiahao16@...wei.com, chenlifu@...wei.com,
        lizhengyu3@...wei.com, liaochang1@...wei.com, wangzhu9@...wei.com,
        xuyihang@...wei.com, chris.zjh@...wei.com, zouyipeng@...wei.com
Subject: Re: [PATCH -next v2] x86/events:Use struct_size() helper in kzalloc()

On Thu, May 19, 2022 at 10:36:00AM +0800, Lin Yujun wrote:
> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows that,
> in the worst scenario, could lead to heap overflows.
> 
> Signed-off-by: Lin Yujun <linyujun809@...wei.com>
> ---
>  arch/x86/events/rapl.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
> index 77e3a47af5ad..8da003e02010 100644
> --- a/arch/x86/events/rapl.c
> +++ b/arch/x86/events/rapl.c
> @@ -683,10 +683,8 @@ static const struct attribute_group *rapl_attr_update[] = {
>  static int __init init_rapl_pmus(void)
>  {
>  	int maxdie = topology_max_packages() * topology_max_die_per_package();
> -	size_t size;
>  
> -	size = sizeof(*rapl_pmus) + maxdie * sizeof(struct rapl_pmu *);
> -	rapl_pmus = kzalloc(size, GFP_KERNEL);
> +	rapl_pmus = kzalloc(struct_size(rapl_pmus, pmus, maxdie), GFP_KERNEL);

So I really hate that thing; it's pointless obfuscation. If you're
really worried about the type confusion, write it like:

	size = sizeof(*rapl_pmus) + sizeof(rapl_pmus->pmus[0]) * maxdie;

or something. Otherwise, just go away.