Subject: Re: [PATCH] Libertas: fix buffer overflow in lbs_get_essid()

From: Daniel Mack <[email-masked]>
Date: Thu, 17 Dec 2009 07:15:08 +0800

On Wed, Dec 16, 2009 at 08:57:47AM -0800, Dan Williams wrote:
> On Wed, 2009-12-16 at 05:12 +0100, Daniel Mack wrote:
> > The libertas driver copies the SSID buffer back to the wireless core and
> > appends a trailing NULL character for termination. This is
> > 
> > a) unnecessary because the buffer is allocated with kzalloc and is hence
> >    already NULLed when this function is called, and
> > 
> > b) for priv->curbssparams.ssid_len == 32, it writes back one byte too
> >    much which causes memory corruptions.
> > 
> > Fix this by removing the extra write.
> 
> Acked-by: Dan Williams <[email-masked]>

Thanks, everyone. Who will care to pick an queue this one?

Daniel

> > Signed-off-by: Daniel Mack <[email-masked]>
> > Cc: Dan Williams <[email-masked]>
> > Cc: Holger Schurig <[email-masked]>
> > Cc: John W. Linville <[email-masked]>
> > Cc: Stephen Hemminger <[email-masked]>
> > Cc: Maithili Hinge <[email-masked]>
> > Cc: Kiran Divekar <[email-masked]>
> > Cc: Michael Hirsch <[email-masked]>
> > Cc: [email-masked]
> > Cc: [email-masked]
> > Cc: [email-masked]
> > Cc: [email-masked]
> > ---
> >  drivers/net/wireless/libertas/wext.c |    2 --
> >  1 files changed, 0 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/wireless/libertas/wext.c b/drivers/net/wireless/libertas/wext.c
> > index be837a0..01c738b 100644
> > --- a/drivers/net/wireless/libertas/wext.c
> > +++ b/drivers/net/wireless/libertas/wext.c
> > @@ -1953,10 +1953,8 @@ static int lbs_get_essid(struct net_device *dev, struct iw_request_info *info,
> >  	if (priv->connect_status == LBS_CONNECTED) {
> >  		memcpy(extra, priv->curbssparams.ssid,
> >  		       priv->curbssparams.ssid_len);
> > -		extra[priv->curbssparams.ssid_len] = '\0';
> >  	} else {
> >  		memset(extra, 0, 32);
> > -		extra[priv->curbssparams.ssid_len] = '\0';
> >  	}
> >  	/*
> >  	 * If none, we may want to get the one that was set
>