linux-kernel - Re: [PATCH 1/9 v2] staging: dt3155: check put

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Date:	Mon, 2 Aug 2010 21:41:25 +0900
From:	Simon Horman <horms@...ge.net.au>
To:	Kulikov Vasiliy <segooon@...il.com>
Cc:	kernel-janitors@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...e.de>,
	H Hartley Sweeten <hsweeten@...ionengravers.com>,
	Joe Eloff <kagen101@...il.com>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/9 v2] staging: dt3155: check put_user() return value

On Mon, Aug 02, 2010 at 12:31:12PM +0400, Kulikov Vasiliy wrote:
> put_user() return code was not checked for errors. To simplify the code
> fill local struct dt3155_read with data and copy it with single
> copy_to_user() call.
> 
> Signed-off-by: Kulikov Vasiliy <segooon@...il.com>
> ---
>  drivers/staging/dt3155/dt3155_drv.c |   17 ++++++++---------
>  1 files changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/staging/dt3155/dt3155_drv.c b/drivers/staging/dt3155/dt3155_drv.c
> index 7316996..4013f09 100644
> --- a/drivers/staging/dt3155/dt3155_drv.c
> +++ b/drivers/staging/dt3155/dt3155_drv.c
> @@ -745,10 +745,11 @@ static ssize_t dt3155_read(struct file *filep, char __user *buf,
>    struct dt3155_status *dts = &dt3155_status[minor];
>    struct dt3155_fbuffer *fb = &dts->fbuffer;
>    struct frame_info	*frame_info;
> +  struct dt3155_read dt_read;
>  
>    /* TODO: this should check the error flag and */
>    /*   return an error on hardware failures */
> -  if (count != sizeof(struct dt3155_read))
> +  if (count != sizeof(dt_read))

I believe that sizeof(struct dt3155_read) is preferred,
so this change isn't needed and sizeof(struct dt3155_read)
should be used below (three times).

>      {
>        printk(KERN_INFO "DT3155 ERROR (NJC): count is not right\n");
>        return -EINVAL;
> @@ -797,17 +798,15 @@ static ssize_t dt3155_read(struct file *filep, char __user *buf,
>  
>    /* make this an offset */
>    offset = frame_info->addr - dts->mem_addr;
> +  dt_read.offset = offset;
> +  dt_read.frame_seq = fb->frame_count;
> +  dt_read.state = dts->state;
> +  memcpy(&dt_read.frame_info, frame_info, sizeof(frame_info));
>  
> -  put_user(offset, (unsigned int __user *)buf);
> -  buf += sizeof(u32);
> -  put_user(fb->frame_count, (unsigned int __user *)buf);
> -  buf += sizeof(u32);
> -  put_user(dts->state, (unsigned int __user *)buf);
> -  buf += sizeof(u32);
> -  if (copy_to_user(buf, frame_info, sizeof(*frame_info)))
> +  if (copy_to_user(buf, &dt_read, sizeof(dt_read)))
>        return -EFAULT;
>  
> -  return sizeof(struct dt3155_read);
> +  return sizeof(dt_read);
>  }
>  
>  static unsigned int dt3155_poll (struct file * filp, poll_table *wait)
> -- 
> 1.7.0.4
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