From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B30AC43334 for ; Mon, 20 Jun 2022 14:59:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231474AbiFTO65 (ORCPT ); Mon, 20 Jun 2022 10:58:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56030 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242726AbiFTO6e (ORCPT ); Mon, 20 Jun 2022 10:58:34 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2567201AB for ; Mon, 20 Jun 2022 07:21:13 -0700 (PDT) Received: from [192.168.1.100] (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madras.collabora.co.uk (Postfix) with ESMTPSA id 997DD660159D; Mon, 20 Jun 2022 15:21:11 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1655734871; bh=1IzybNISo/qb6ajNmb/E3/HYWTJnWgW68XVLtKxjpQw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=R+Zk4qEZVjVF10Y0lFJzWvE1/eed+MdfL/c3tDFkgtrZX38tOIjJd1c0QMXwToIaC uE1XLJ/nHZd95PXP8CzGxccUfszQWWoSnM8RnbHYc+x34QabPELyrevasvliIFGch8 GNHwPT+f3LiQQGOe5OnWPyapchfVR2QY+f7gSg4xIJKP6T+cwiMlQP2dy+QOtLKAxO FbN6trgIEWvQtDucS4hATU3oPsPFqd8uNlExwFbgJ7wTmuU66tvFPdPObEu29ocKe1 m+ehzep8YZlO3DjSQuuy/eTBih8ycSU30gOfHx2F5a90Ksxc+ML7zRRlIXKsEljAwE NufvhcuMZ4xmA== Message-ID: <25da54a7-3fc1-39c2-ed93-0ad72ce54e11@collabora.com> Date: Mon, 20 Jun 2022 16:21:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH] PM / devfreq: mediatek: Fix possible dereference of null pointer Content-Language: en-US To: matthias.bgg@kernel.org, dan.carpenter@oracle.com, johnson.wang@mediatek.com Cc: linux-pm@vger.kernel.org, linux-mediatek@lists.infradead.org, Matthias Brugger References: <20220617133330.6510-1-matthias.bgg@kernel.org> From: AngeloGioacchino Del Regno In-Reply-To: <20220617133330.6510-1-matthias.bgg@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Il 17/06/22 15:33, matthias.bgg@kernel.org ha scritto: > From: Matthias Brugger > > We dereference the driver data before checking of it's valid. > This patch fixes this, by accessing the PLL data struct after cheching > the pointer > Hello Matthias, honestly, I don't think that this commit is right: mtk_ccifreq_target() is the devfreq_dev_profile's .target() callback! Checking mtk_ccifreq_probe(), we are setting drvdata long before adding the devfreq device so, actually, it's impossible for dev_get_drvdata(dev) to return NULL, or whatever invalid pointer. This means that the right thing to do in mtk_ccifreq_target() is to simply remove the `drv` NULL check, as this can never happen! :-) Cheers, Angelo > Fixes: 07dc787be231 ("Add linux-next specific files for 20220617") > Signed-off-by: Matthias Brugger > --- > drivers/devfreq/mtk-cci-devfreq.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/devfreq/mtk-cci-devfreq.c b/drivers/devfreq/mtk-cci-devfreq.c > index 71abb3fbd042..77522f16c878 100644 > --- a/drivers/devfreq/mtk-cci-devfreq.c > +++ b/drivers/devfreq/mtk-cci-devfreq.c > @@ -127,7 +127,7 @@ static int mtk_ccifreq_target(struct device *dev, unsigned long *freq, > u32 flags) > { > struct mtk_ccifreq_drv *drv = dev_get_drvdata(dev); > - struct clk *cci_pll = clk_get_parent(drv->cci_clk); > + struct clk *cci_pll; > struct dev_pm_opp *opp; > unsigned long opp_rate; > int voltage, pre_voltage, inter_voltage, target_voltage, ret; > @@ -138,6 +138,7 @@ static int mtk_ccifreq_target(struct device *dev, unsigned long *freq, > if (drv->pre_freq == *freq) > return 0; > > + cci_pll = clk_get_parent(drv->cci_clk); > inter_voltage = drv->inter_voltage; > > opp_rate = *freq; >