linux-kernel - Re: [PATCH V3 2/2] Move stack parameters for sed_ioctl to prevent oversized stack with CONFIG

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Date:   Fri, 10 Feb 2017 08:45:38 +0100
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     Scott Bauer <scott.bauer@...el.com>, linux-nvme@...ts.infradead.org
Cc:     David.Laight@...LAB.COM, arnd@...db.de, axboe@...com,
        keith.busch@...el.com, jonathan.derrick@...el.com,
        hch@...radead.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org
Subject: Re: [PATCH V3 2/2] Move stack parameters for sed_ioctl to prevent
 oversized stack with CONFIG_KASAN

On 02/09/2017 06:20 PM, Scott Bauer wrote:
> When CONFIG_KASAN is enabled, compilation fails:
> 
> block/sed-opal.c: In function 'sed_ioctl':
> block/sed-opal.c:2447:1: error: the frame size of 2256 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
> 
> Moved all the ioctl structures off the stack and dynamically activate
> using _IOC_SIZE()
> 
> Fixes: 455a7b238cd6 ("block: Add Sed-opal library")
> 
> Reported-by: Arnd Bergmann <arnd@...db.de>
> Signed-off-by: Scott Bauer <scott.bauer@...el.com>
> ---
>  block/sed-opal.c | 134 +++++++++++++++++++++----------------------------------
>  1 file changed, 50 insertions(+), 84 deletions(-)
> 

[...]

> -		if (copy_from_user(&session, arg, sizeof(session)))
> -			return -EFAULT;
> -		return opal_erase_locking_range(dev, &session);
> +	ioctl_ptr = kzalloc(cmd_size, GFP_KERNEL);
> +	if (!ioctl_ptr)
> +		return -ENOMEM;
> +	if (copy_from_user(ioctl_ptr, arg, cmd_size)) {
> +		ret = -EFAULT;
> +		goto out;
>  	}

Can't we use memdup_user() instead of kzalloc() + copy_from_user()?



-- 
Johannes Thumshirn                                          Storage
jthumshirn@...e.de                                +49 911 74053 689
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