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Message-ID: <cafcc2b1-2b9b-4957-ee8a-9e260a7e2f5d@mev.co.uk>
Date:   Tue, 7 Jun 2022 13:30:59 +0100
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Subject: Re: [PATCH 1/1] comedi: ni_usb6501: fix transfer-buffer overflows
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To:     Xiaohui Zhang <xiaohuizhang@ruc.edu.cn>,
        H Hartley Sweeten <hsweeten@visionengravers.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Johan Hovold <johan@kernel.org>, linux-kernel@vger.kernel.org
References: <20220607111802.13311-1-xiaohuizhang@ruc.edu.cn>
From:   Ian Abbott <abbotti@mev.co.uk>
Organization: MEV Ltd.
In-Reply-To: <20220607111802.13311-1-xiaohuizhang@ruc.edu.cn>
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On 07/06/2022 12:18, Xiaohui Zhang wrote:
> Similar to the handling of vmk80xx_alloc_usb_buffers in commit
> a23461c47482("comedi: vmk80xx: fix transfer-buffer overflows"),
> we thought a patch might be needed here as well.
> 
> The driver uses endpoint-sized USB transfer buffers but up until
> recently had no sanity checks on the sizes.
> 
> Signed-off-by: Xiaohui Zhang <xiaohuizhang@ruc.edu.cn>
> ---
>   drivers/comedi/drivers/ni_usb6501.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/comedi/drivers/ni_usb6501.c b/drivers/comedi/drivers/ni_usb6501.c
> index 0dd9edf7bced..8303bfc305c5 100644
> --- a/drivers/comedi/drivers/ni_usb6501.c
> +++ b/drivers/comedi/drivers/ni_usb6501.c
> @@ -90,6 +90,7 @@
>   #include <linux/comedi/comedi_usb.h>
>   
>   #define	NI6501_TIMEOUT	1000
> +#define MIN_BUF_SIZE	64
>   
>   /* Port request packets */
>   static const u8 READ_PORT_REQUEST[]	= {0x00, 0x01, 0x00, 0x10,
> @@ -459,12 +460,12 @@ static int ni6501_alloc_usb_buffers(struct comedi_device *dev)
>   	struct ni6501_private *devpriv = dev->private;
>   	size_t size;
>   
> -	size = usb_endpoint_maxp(devpriv->ep_rx);
> +	size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE);
>   	devpriv->usb_rx_buf = kzalloc(size, GFP_KERNEL);
>   	if (!devpriv->usb_rx_buf)
>   		return -ENOMEM;
>   
> -	size = usb_endpoint_maxp(devpriv->ep_tx);
> +	size = max(usb_endpoint_maxp(devpriv->ep_tx), MIN_BUF_SIZE);
>   	devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL);
>   	if (!devpriv->usb_tx_buf)
>   		return -ENOMEM;

The code change looks OK but this patch should have been sent as a "v2" 
patch and should have a brief description of the v2 changes after the 
"---" line.

Reviewed-by: Ian Abbott <abbotti@mev.co.uk>

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