linux-kernel - Re: [PATCH v4 6/6] powerpc/eeh-powernv: fix potential OoB

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Message-ID: <3wfa4z2uozeg4bhu47uipn7mqjuaspxxvjsb7gfpwxbgjfivat@lr6lh5gpht7m>
Date: Tue, 20 May 2025 08:48:57 +0530
From: Mahesh J Salgaonkar <mahesh@...ux.ibm.com>
To: Markus Burri <markus.burri@...com>
Cc: linux-kernel@...r.kernel.org, "Oliver O'Halloran" <oohall@...il.com>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Naveen N Rao <naveen@...nel.org>,
        Jacek Lawrynowicz <jacek.lawrynowicz@...ux.intel.com>,
        Maciej Falkowski <maciej.falkowski@...ux.intel.com>,
        Oded Gabbay <ogabbay@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>, Nuno Sa <nuno.sa@...log.com>,
        Olivier Moysan <olivier.moysan@...s.st.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>, linuxppc-dev@...ts.ozlabs.org,
        dri-devel@...ts.freedesktop.org, linux-gpio@...r.kernel.org,
        linux-iio@...r.kernel.org, Markus Burri <markus.burri@....ch>
Subject: Re: [PATCH v4 6/6] powerpc/eeh-powernv: fix potential OoB

On 2025-05-08 15:06:12 Thu, Markus Burri wrote:
> The buffer is set to 50 characters. If a caller write more characters,
> count is truncated to the max available space in "simple_write_to_buffer".
> To protect from OoB access, check that the input size fit into buffer and
> add a zero terminator after copy to the end of the copied data.
> 
> Signed-off-by: Markus Burri <markus.burri@...com>

Looks perfect to me.

Acked-by: Mahesh Salgaonkar <mahesh@...ux.ibm.com>

Thanks,
-Mahesh.

> ---
>  arch/powerpc/platforms/powernv/eeh-powernv.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c b/arch/powerpc/platforms/powernv/eeh-powernv.c
> index db3370d1673c..3abee21fdd05 100644
> --- a/arch/powerpc/platforms/powernv/eeh-powernv.c
> +++ b/arch/powerpc/platforms/powernv/eeh-powernv.c
> @@ -73,14 +73,19 @@ static ssize_t pnv_eeh_ei_write(struct file *filp,
>  	char buf[50];
>  	int ret;
>  
> +	if (count >= sizeof(buf))
> +		return -EINVAL;
> +
>  	if (!eeh_ops || !eeh_ops->err_inject)
>  		return -ENXIO;
>  
>  	/* Copy over argument buffer */
> -	ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);
> +	ret = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, user_buf, count);
>  	if (!ret)
>  		return -EFAULT;
>  
> +	buf[ret] = '\0';
> +
>  	/* Retrieve parameters */
>  	ret = sscanf(buf, "%x:%x:%x:%lx:%lx",
>  		     &pe_no, &type, &func, &addr, &mask);
> -- 
> 2.39.5
> 
> 

-- 
Mahesh J Salgaonkar