Re: [PATCH -next] sched: Use struct_size() helper in task_numa_group()

From: Steven Rostedt <rostedt@goodmis.org>
To: Xiu Jianfeng <xiujianfeng@huawei.com>
Cc: <mingo@redhat.com>, <peterz@infradead.org>,
	<juri.lelli@redhat.com>, <vincent.guittot@linaro.org>,
	<dietmar.eggemann@arm.com>, <bsegall@google.com>,
	<mgorman@suse.de>, <bristot@redhat.com>, <gustavoars@kernel.org>,
	<linux-kernel@vger.kernel.org>, <linux-hardening@vger.kernel.org>
Subject: Re: [PATCH -next] sched: Use struct_size() helper in task_numa_group()
Date: Fri, 7 Jan 2022 09:36:17 -0500	[thread overview]
Message-ID: <20220107093617.56e218dc@gandalf.local.home> (raw)
In-Reply-To: <20220107025212.177040-1-xiujianfeng@huawei.com>

On Fri, 7 Jan 2022 10:52:12 +0800
Xiu Jianfeng <xiujianfeng@huawei.com> wrote:

> Make use of struct_size() helper instead of an open-coded calculation.
> There is no functional change in this patch.
> 
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
> ---
>  kernel/sched/fair.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 095b0aa378df..265e37be0c92 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2437,11 +2437,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
>  	int i;
>  
>  	if (unlikely(!deref_curr_numa_group(p))) {
> -		unsigned int size = sizeof(struct numa_group) +
> -				    NR_NUMA_HINT_FAULT_STATS *
> -				    nr_node_ids * sizeof(unsigned long);
> -
> -		grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
> +		grp = kzalloc(struct_size(grp, faults, NR_NUMA_HINT_FAULT_STATS * nr_node_ids),
> +			      GFP_KERNEL | __GFP_NOWARN);

I just replied yesterday. Keep the size variable. The above is too much for
a kzalloc().

-- Steve

>  		if (!grp)
>  			return;
>  