netdev - Re: [patch] isdn: fix information leak

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Message-ID: <20100805101938.GH9031@bicker>
Date:	Thu, 5 Aug 2010 12:19:38 +0200
From:	Dan Carpenter <error27@...il.com>
To:	Changli Gao <xiaosuo@...il.com>
Cc:	Karsten Keil <isdn@...ux-pingi.de>, netdev@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch] isdn: fix information leak

On Thu, Aug 05, 2010 at 06:08:08PM +0800, Changli Gao wrote:
> On Thu, Aug 5, 2010 at 5:38 PM, Dan Carpenter <error27@...il.com> wrote:
> > The main motivation of this patch changing strcpy() to strlcpy().
> > We strcpy() to copy a 48 byte buffers into a 49 byte buffers.  So at
> > best the last byte has leaked information, or maybe there is an
> > overflow?  Anyway, this patch closes the information leaks by zeroing
> > the memory and the calls to strlcpy() prevent overflows.
> 
> strlcpy() can handle the terminator NUL. so you don't need to zero it.

If there are no NUL chars in "rcvmsg->msg_data.byte_array" then strlcpy()
is sufficient, but if there is a NUL character then you need to zero the
memory.  The patch handles both possibilities.

regards,
dan carpenter

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