linux-kernel - Re: [PATCH v2] x86/resctrl: Avoid overflow in MB settings in bw

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Message-ID: <dd3731ef-cf47-4103-a310-13536e831bc2@intel.com>
Date: Mon, 23 Sep 2024 09:50:40 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Martin Kletzander <nert.pinx@...il.com>
CC: Fenghua Yu <fenghua.yu@...el.com>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, <x86@...nel.org>, "H. Peter Anvin"
	<hpa@...or.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] x86/resctrl: Avoid overflow in MB settings in
 bw_validate()

Hi Martin,

On 9/17/24 10:19 AM, Reinette Chatre wrote:
> On 9/17/24 8:47 AM, Martin Kletzander wrote:
>> I wanted but the diff has some weird line numbering and could not be
>> applied.  I'll write it manually later, test it out, and send a v3.
>> Thanks!
> 
> Apologies. Please try:
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index 50fa1fe9a073..53defc5a6784 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -29,10 +29,10 @@
>   * hardware. The allocated bandwidth percentage is rounded to the next
>   * control step available on the hardware.
>   */
> -static bool bw_validate(char *buf, unsigned long *data, struct rdt_resource *r)
> +static bool bw_validate(char *buf, u32 *data, struct rdt_resource *r)
>  {
> -	unsigned long bw;
>  	int ret;
> +	u32 bw;
>  
>  	/*
>  	 * Only linear delay values is supported for current Intel SKUs.
> @@ -42,14 +42,19 @@ static bool bw_validate(char *buf, unsigned long *data, struct rdt_resource *r)
>  		return false;
>  	}
>  
> -	ret = kstrtoul(buf, 10, &bw);
> +	ret = kstrtou32(buf, 10, &bw);
>  	if (ret) {
> -		rdt_last_cmd_printf("Non-decimal digit in MB value %s\n", buf);
> +		rdt_last_cmd_printf("Invalid MB value %s\n", buf);
>  		return false;
>  	}
>  
> -	if ((bw < r->membw.min_bw || bw > r->default_ctrl) &&
> -	    !is_mba_sc(r)) {
> +	/* Nothing else to do if software controller is enabled. */
> +	if (is_mba_sc(r)) {
> +		*data = bw;
> +		return true;
> +	}
> +
> +	if (bw < r->membw.min_bw || bw > r->default_ctrl) {
>  		rdt_last_cmd_printf("MB value %ld out of range [%d,%d]\n", bw,
>  				    r->membw.min_bw, r->default_ctrl);
>  		return false;
> @@ -65,7 +70,7 @@ int parse_bw(struct rdt_parse_data *data, struct resctrl_schema *s,
>  	struct resctrl_staged_config *cfg;
>  	u32 closid = data->rdtgrp->closid;
>  	struct rdt_resource *r = s->res;
> -	unsigned long bw_val;
> +	u32 bw_val;
>  
>  	cfg = &d->staged_config[s->conf_type];
>  	if (cfg->have_new_ctrl) {
> 

If you do find this appropriate you are welcome to add:

Co-developed-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette