Message-ID: <290b055f-9fc1-2580-244f-24663fba171f@igalia.com>
Date:   Fri, 24 Feb 2023 01:00:41 -0300
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Subject: Re: [PATCH v1 1/1] pstore/ram: Fix crash when setting number of cpus
 to an odd number
Content-Language: en-US
To:     Weichen Chen <weichen.chen@mediatek.com>,
        linux-hardening@vger.kernel.org
References: <20230224023632.6840-1-weichen.chen@mediatek.com>
Cc:     linux-kernel@vger.kernel.org, yt.shen@mediatek.com,
        matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com,
        tony.luck@intel.com, keescook@chromium.org,
        darren.chen@mediatek.com
From:   "Guilherme G. Piccoli" <gpiccoli@igalia.com>
In-Reply-To: <20230224023632.6840-1-weichen.chen@mediatek.com>
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Precedence: bulk

On 23/02/2023 23:36, Weichen Chen wrote:
> When the number of cpu cores is adjusted to 7 or other odd numbers,
> the zone size will become an odd number.
> The address of the zone will become:
>     addr of zone0 = BASE
>     addr of zone1 = BASE + zone_size
>     addr of zone2 = BASE + zone_size*2
>     ...
> The address of zone1/3/5/7 will be mapped to non-alignment va.
> Eventually crashes will occur when accessing these va.
> 
> So, use ALIGN_DOWN() to make sure the zone size is even
> to avoid this bug.
> 
> Signed-off-by: Weichen Chen <weichen.chen@mediatek.com>
> ---
>  fs/pstore/ram.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index ade66dbe5f39..fc57ac97e506 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -528,6 +528,7 @@ static int ramoops_init_przs(const char *name,
>  	}
>  
>  	zone_sz = mem_sz / *cnt;
> +	zone_sz = ALIGN_DOWN(zone_sz, 2);
>  	if (!zone_sz) {
>  		dev_err(dev, "%s zone size == 0\n", name);
>  		goto fail;

Thanks for resending! Feel free to add my:

Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

Cheers,


Guilherme