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

[Mahesh J Salgaonkar]

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 at mt.com>

Looks perfect to me.

Acked-by: Mahesh Salgaonkar <mahesh at linux.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