linux-kernel - Re: [PATCH] Staging: dgnc: Using temporary value for repeated dereferences.

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Date:	Sun, 19 Apr 2015 17:54:19 -0700
From:	Joe Perches <joe@...ches.com>
To:	Yorick Rommers <yorick-rommers@...mail.com>
Cc:	lidza.louina@...il.com, gregkh@...uxfoundation.org,
	markh@...pro.net, driverdev-devel@...uxdriverproject.org,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Staging: dgnc: Using temporary value for repeated
 dereferences.

On Sun, 2015-04-19 at 23:58 +0200, Yorick Rommers wrote:
> Hello Joe,
> 
> Thank you once again for the feedback.
> I've changed my patch accordingly, see below.
> 
> --------------------------------------
> 
> A patch for a line being too long (>80) in dgnc_mgmt.c,
> fixed by making a temporary value for dgnc_Board[brd],
> replacing all instanced of dgnc_Board[brd] with temporary value,
> and removing unnecessary typecasts.
> 
> Signed-off-by: Yorick Rommers <yorick-rommers@...mail.com>
> ---
>  drivers/staging/dgnc/dgnc_mgmt.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/dgnc/dgnc_mgmt.c b/drivers/staging/dgnc/dgnc_mgmt.c
> index b13318a..0437117 100644
> --- a/drivers/staging/dgnc/dgnc_mgmt.c
> +++ b/drivers/staging/dgnc/dgnc_mgmt.c
> @@ -131,6 +131,7 @@ long dgnc_mgmt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>  		int brd;
> 
>  		struct digi_info di;
> +		struct dgnc_board *bd = dgnc_Board[brd];

Please read the code.
brd is got from userspace and you've dereferenced
it before getting the value from userspace.

>  		if (copy_from_user(&brd, uarg, sizeof(int)))
>  			return -EFAULT;

Look again at the code I suggested.


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