linux-kernel - Re: [PATCH v1] tools/power: turbostat: fix buffer overrun

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Message-ID: <f3ff449d-f431-4ea6-5c3f-8e19e2c534a8@redhat.com>
Date:   Wed, 3 Apr 2019 07:42:45 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        linux-pm@...r.kernel.org
Cc:     Len Brown <len.brown@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] tools/power: turbostat: fix buffer overrun



On 4/3/19 3:02 AM, Naoya Horiguchi wrote:
> turbostat could be terminated by general protection fault on some latest
> hardwares which (for example) support 9 levels of C-states and show 18
> "tADDED" lines. That bloats the total output and finally causes buffer
> overrun.  So let's extend the buffer to avoid this.
> 
> This patch also removes duplicated "pc10:" line to reduce buffer usage.
> 
> Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> ---
>  tools/power/x86/turbostat/turbostat.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git v5.1-rc3-mmotm-2019-04-02-17-16/tools/power/x86/turbostat/turbostat.c v5.1-rc3-mmotm-2019-04-02-17-16_patched/tools/power/x86/turbostat/turbostat.c
> index c7727be..17b1f544 100644
> --- v5.1-rc3-mmotm-2019-04-02-17-16/tools/power/x86/turbostat/turbostat.c
> +++ v5.1-rc3-mmotm-2019-04-02-17-16_patched/tools/power/x86/turbostat/turbostat.c
> @@ -861,7 +861,6 @@ int dump_counters(struct thread_data *t, struct core_data *c,
>  		outp += sprintf(outp, "pc8: %016llX\n", p->pc8);
>  		outp += sprintf(outp, "pc9: %016llX\n", p->pc9);
>  		outp += sprintf(outp, "pc10: %016llX\n", p->pc10);
> -		outp += sprintf(outp, "pc10: %016llX\n", p->pc10);
>  		outp += sprintf(outp, "cpu_lpi: %016llX\n", p->cpu_lpi);
>  		outp += sprintf(outp, "sys_lpi: %016llX\n", p->sys_lpi);
>  		outp += sprintf(outp, "Joules PKG: %0X\n", p->energy_pkg);
> @@ -5135,7 +5134,7 @@ int initialize_counters(int cpu_id)
>  
>  void allocate_output_buffer()
>  {
> -	output_buffer = calloc(1, (1 + topo.num_cpus) * 1024);
> +	output_buffer = calloc(1, (1 + topo.num_cpus) * 2048);

Is there a better way to calculate the size of that buffer other than a magic
number?

P.

>  	outp = output_buffer;
>  	if (outp == NULL)
>  		err(-1, "calloc output buffer");
>