Subject: Re: [PATCH RESEND] dm9601: don't do usb transfers of data on stack

From: David Brownell <david-b-yBeKhBN/[email-masked]>
Date: Fri, 11 Jul 2008 15:02:20 -0700

On Friday 11 July 2008, Peter Korsgaard wrote:
> dm_{read,write}() were doing USB transfers of data on stack, which isn't
> allowed. Fix it by kmalloc'ing a temporary buffer.
> Clean up the error handling for short transfers while we're at it.
> 
> Signed-off-by: Peter Korsgaard <jacmet-OfajU3CKLf1/[email-masked]>

Acked-by: David Brownell <[email-masked]>

> ---
>  drivers/net/usb/dm9601.c |   52 +++++++++++++++++++++++++++++++++++++--------
>  1 files changed, 42 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/usb/dm9601.c b/drivers/net/usb/dm9601.c
> index f7319d3..78df2be 100644
> --- a/drivers/net/usb/dm9601.c
> +++ b/drivers/net/usb/dm9601.c
> @@ -55,12 +55,28 @@
>  
>  static int dm_read(struct usbnet *dev, u8 reg, u16 length, void *data)
>  {
> +	void *buf;
> +	int err = -ENOMEM;
> +
>  	devdbg(dev, "dm_read() reg=0x%02x length=%d", reg, length);
> -	return usb_control_msg(dev->udev,
> -			       usb_rcvctrlpipe(dev->udev, 0),
> -			       DM_READ_REGS,
> -			       USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> -			       0, reg, data, length, USB_CTRL_SET_TIMEOUT);
> +
> +	buf = kmalloc(length, GFP_KERNEL);
> +	if (!buf)
> +		goto out;
> +
> +	err = usb_control_msg(dev->udev,
> +			      usb_rcvctrlpipe(dev->udev, 0),
> +			      DM_READ_REGS,
> +			      USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> +			      0, reg, buf, length, USB_CTRL_SET_TIMEOUT);
> +	if (err == length)
> +		memcpy(data, buf, length);
> +	else if (err >= 0)
> +		err = -EINVAL;
> +	kfree(buf);
> +
> + out:
> +	return err;
>  }
>  
>  static int dm_read_reg(struct usbnet *dev, u8 reg, u8 *value)
> @@ -70,12 +86,28 @@ static int dm_read_reg(struct usbnet *dev, u8 reg, u8 *value)
>  
>  static int dm_write(struct usbnet *dev, u8 reg, u16 length, void *data)
>  {
> +	void *buf = NULL;
> +	int err = -ENOMEM;
> +
>  	devdbg(dev, "dm_write() reg=0x%02x, length=%d", reg, length);
> -	return usb_control_msg(dev->udev,
> -			       usb_sndctrlpipe(dev->udev, 0),
> -			       DM_WRITE_REGS,
> -			       USB_DIR_OUT | USB_TYPE_VENDOR |USB_RECIP_DEVICE,
> -			       0, reg, data, length, USB_CTRL_SET_TIMEOUT);
> +
> +	if (data) {
> +		buf = kmalloc(length, GFP_KERNEL);
> +		if (!buf)
> +			goto out;
> +		memcpy(buf, data, length);
> +	}
> +
> +	err = usb_control_msg(dev->udev,
> +			      usb_sndctrlpipe(dev->udev, 0),
> +			      DM_WRITE_REGS,
> +			      USB_DIR_OUT | USB_TYPE_VENDOR |USB_RECIP_DEVICE,
> +			      0, reg, buf, length, USB_CTRL_SET_TIMEOUT);
> +	kfree(buf);
> +	if (err >= 0 && err < length)
> +		err = -EINVAL;
> + out:
> +	return err;
>  }
>  
>  static int dm_write_reg(struct usbnet *dev, u8 reg, u8 value)
> -- 
> 1.5.6.2
> 
> 
> -- 
> Bye, Peter Korsgaard
> --
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