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

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Message-ID: <20150420083310.GE16501@mwanda>
Date:	Mon, 20 Apr 2015 11:33:10 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Yorick Rommers <yorick-rommers@...mail.com>,
	devel@...verdev.osuosl.org, lidza.louina@...il.com,
	driverdev-devel@...uxdriverproject.org,
	linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org
Subject: Re: [PATCH] Staging: dgnc: Using temporary value for repeated
 dereferences.

On Sun, Apr 19, 2015 at 05:54:19PM -0700, Joe Perches wrote:
> > 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.

Gar.  Oops.  I totally missed that when I looked at this patch.  :(

You would hope that GCC would warn about the uninitialized variable but
it doesn't.


regards,
dan carpenter

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