From mboxrd@z Thu Jan 1 00:00:00 1970 From: LABBE Corentin Subject: Re: [PATCH v2 1/1] pwm: sun4i: fix a possible NULL dereference Date: Wed, 24 Aug 2016 13:42:45 +0200 Message-ID: <20160824114245.GA29212@Red> References: <1471353486-11514-1-git-send-email-clabbe.montjoie@gmail.com> <1471353486-11514-2-git-send-email-clabbe.montjoie@gmail.com> <20160822065737.GA7104@lukather> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-wm0-f66.google.com ([74.125.82.66]:35230 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752485AbcHXLmu (ORCPT ); Wed, 24 Aug 2016 07:42:50 -0400 Content-Disposition: inline In-Reply-To: <20160822065737.GA7104@lukather> Sender: linux-pwm-owner@vger.kernel.org List-Id: linux-pwm@vger.kernel.org To: Maxime Ripard Cc: thierry.reding@gmail.com, wens@csie.org, linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org On Mon, Aug 22, 2016 at 08:57:37AM +0200, Maxime Ripard wrote: > Hi, > > On Tue, Aug 16, 2016 at 03:18:06PM +0200, LABBE Corentin wrote: > > of_match_device could return NULL, and so cause a NULL pointer > > dereference later. > > > > For fixing this problem, we use of_device_get_match_data(), this will > > simplify the code a little by using a standard function for > > getting the match data. > > > > Reported-by: coverity (CID 1324139) > > Signed-off-by: LABBE Corentin > > --- > > drivers/pwm/pwm-sun4i.c | 5 +---- > > 1 file changed, 1 insertion(+), 4 deletions(-) > > > > diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c > > index 03a99a5..72f0060 100644 > > --- a/drivers/pwm/pwm-sun4i.c > > +++ b/drivers/pwm/pwm-sun4i.c > > @@ -309,9 +309,6 @@ static int sun4i_pwm_probe(struct platform_device *pdev) > > struct resource *res; > > u32 val; > > int i, ret; > > - const struct of_device_id *match; > > - > > - match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev); > > > > pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); > > if (!pwm) > > @@ -326,7 +323,7 @@ static int sun4i_pwm_probe(struct platform_device *pdev) > > if (IS_ERR(pwm->clk)) > > return PTR_ERR(pwm->clk); > > > > - pwm->data = match->data; > > + pwm->data = of_device_get_match_data(&pdev->dev); > > How does that fix anything? > > If of_match_data fails, it will return NULL, and the NULL pointer > dereference will occur in the exact same cases. > > You should just check for match to be NULL, and return in this case. > > Maxime > I apologize for havent seen this subsuquent NULL deref. I send an updated version soon. Regards