linux-kernel - Re: [PATCHv2] net: wireless: wcn36xx: fix potential NULL pointer dereference

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Message-ID: <20131206161258.GC13285@tuxdriver.com>
Date:	Fri, 6 Dec 2013 11:12:58 -0500
From:	"John W. Linville" <linville@...driver.com>
To:	Eugene Krasnikov <k.eugene.e@...il.com>
Cc:	Michal Nazarewicz <mina86@...a86.com>,
	Peter Stuge <peter@...ge.se>,
	ath9k-devel <ath9k-devel@...ema.h4ckr.net>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] net: wireless: wcn36xx: fix potential NULL pointer
 dereference

FWIW, I merged the earlier version.  Please send any changes as a
follow-up patch, probably against wireless-next.

John

On Thu, Dec 05, 2013 at 08:41:29AM +0000, Eugene Krasnikov wrote:
> > +               if (msg_ind)
> > +                       break;
> > +               /* FIXME: Do something smarter then just printing an error. */
> > +               wcn36xx_err("Run out of memory while handling SMD_EVENT (%d)\n",
> 
> I think code will look neater if error case will be handled in "else"
> statement something like:
> if (msg_ind) {
> ...
> } else {
> /*print message*/
> }
> /*unlock and break;*/
> 
> How about that?
> 
> 
> On Mon, Dec 2, 2013 at 1:09 PM, Michal Nazarewicz <mina86@...a86.com> wrote:
> >
> > If kmalloc fails wcn36xx_smd_rsp_process will attempt to dereference
> > a NULL pointer.  There might be a better error recovery then just
> > printing an error, but printing an error message is better then the
> > current behaviour.
> >
> > Signed-off-by: Michal Nazarewicz <mina86@...a86.com>
> > ---
> >  drivers/net/wireless/ath/wcn36xx/smd.c | 19 +++++++++++++------
> >  1 file changed, 13 insertions(+), 6 deletions(-)
> >
> > On Sun, Dec 01 2013, Peter Stuge wrote:
> >> Michal Nazarewicz wrote:
> >>> +                    wcn36xx_err("Run out of memory while hnadling SMD_EVENT (%d)\n",
> >>> +                                msg_header->msg_type);
> >>
> >> Typo hnadling.
> >
> > Fixed.
> >
> > diff --git a/drivers/net/wireless/ath/wcn36xx/smd.c b/drivers/net/wireless/ath/wcn36xx/smd.c
> > index de9eb2c..3663394 100644
> > --- a/drivers/net/wireless/ath/wcn36xx/smd.c
> > +++ b/drivers/net/wireless/ath/wcn36xx/smd.c
> > @@ -2041,13 +2041,20 @@ static void wcn36xx_smd_rsp_process(struct wcn36xx *wcn, void *buf, size_t len)
> >         case WCN36XX_HAL_DELETE_STA_CONTEXT_IND:
> >                 mutex_lock(&wcn->hal_ind_mutex);
> >                 msg_ind = kmalloc(sizeof(*msg_ind), GFP_KERNEL);
> > -               msg_ind->msg_len = len;
> > -               msg_ind->msg = kmalloc(len, GFP_KERNEL);
> > -               memcpy(msg_ind->msg, buf, len);
> > -               list_add_tail(&msg_ind->list, &wcn->hal_ind_queue);
> > -               queue_work(wcn->hal_ind_wq, &wcn->hal_ind_work);
> > -               wcn36xx_dbg(WCN36XX_DBG_HAL, "indication arrived\n");
> > +               if (msg_ind) {
> > +                       msg_ind->msg_len = len;
> > +                       msg_ind->msg = kmalloc(len, GFP_KERNEL);
> > +                       memcpy(msg_ind->msg, buf, len);
> > +                       list_add_tail(&msg_ind->list, &wcn->hal_ind_queue);
> > +                       queue_work(wcn->hal_ind_wq, &wcn->hal_ind_work);
> > +                       wcn36xx_dbg(WCN36XX_DBG_HAL, "indication arrived\n");
> > +               }
> >                 mutex_unlock(&wcn->hal_ind_mutex);
> > +               if (msg_ind)
> > +                       break;
> > +               /* FIXME: Do something smarter then just printing an error. */
> > +               wcn36xx_err("Run out of memory while handling SMD_EVENT (%d)\n",
> > +                           msg_header->msg_type);
> >                 break;
> >         default:
> >                 wcn36xx_err("SMD_EVENT (%d) not supported\n",
> > --
> > 1.8.4.1
> >
> > --
> > Best regards,                                         _     _
> > .o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
> > ..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
> > ooo +--<mpn@...gle.com>--<xmpp:mina86@...ber.org>--ooO--(_)--Ooo--
> 
> 
> 
> -- 
> Best regards,
> Eugene
> 

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