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

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

[Daniel Mack]

(Sorry, had a typo in the linux-wireless list address, corrected now).

On Wed, Dec 16, 2009 at 05:12:58AM +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.
> 
> Signed-off-by: Daniel Mack <daniel@caiaq.de>
> Cc: Dan Williams <dcbw@redhat.com>
> Cc: Holger Schurig <holgerschurig@gmail.com>
> Cc: John W. Linville <linville@tuxdriver.com>
> Cc: Stephen Hemminger <shemminger@vyatta.com>
> Cc: Maithili Hinge <maithili@marvell.com>
> Cc: Kiran Divekar <dkiran@marvell.com>
> Cc: Michael Hirsch <m.hirsch@raumfeld.com>
> Cc: netdev@vger.kernel.org
> Cc: libertas-dev@lists.infradead.org
> Cc: linux-wireless@lists.infradead.org
> Cc: stable@kernel.org
> ---
>  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
> -- 
> 1.6.3.3
> 

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

[Daniel Mack]

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 <dcbw@redhat.com>

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

Daniel


> > Signed-off-by: Daniel Mack <daniel@caiaq.de>
> > Cc: Dan Williams <dcbw@redhat.com>
> > Cc: Holger Schurig <holgerschurig@gmail.com>
> > Cc: John W. Linville <linville@tuxdriver.com>
> > Cc: Stephen Hemminger <shemminger@vyatta.com>
> > Cc: Maithili Hinge <maithili@marvell.com>
> > Cc: Kiran Divekar <dkiran@marvell.com>
> > Cc: Michael Hirsch <m.hirsch@raumfeld.com>
> > Cc: netdev@vger.kernel.org
> > Cc: libertas-dev@lists.infradead.org
> > Cc: linux-wireless@lists.infradead.org
> > Cc: stable@kernel.org
> > ---
> >  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
> 

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

[John W. Linville]

On Thu, Dec 17, 2009 at 07:15:08AM +0800, Daniel Mack wrote:
> 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 <dcbw@redhat.com>
> 
> Thanks, everyone. Who will care to pick an queue this one?

Is there some reason it wouldn't be me?

John
-- 
John W. Linville                Someday the world will need a hero, and you
linville@tuxdriver.com                  might be all we have.  Be ready.

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

[Dan Williams]

On Wed, 2009-12-16 at 20:01 -0500, John W. Linville wrote:
> On Thu, Dec 17, 2009 at 07:15:08AM +0800, Daniel Mack wrote:
> > 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 <dcbw@redhat.com>
> > 
> > Thanks, everyone. Who will care to pick an queue this one?
> 
> Is there some reason it wouldn't be me?

No, it should be you.  Please suck it into your 2.6.33 patchset and
we'll cc to stable when it hits linus I guess.

Dan