From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933074AbeEWNmh (ORCPT ); Wed, 23 May 2018 09:42:37 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:52950 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932900AbeEWNme (ORCPT ); Wed, 23 May 2018 09:42:34 -0400 X-Google-Smtp-Source: AB8JxZowjuTOQMfgs0d3TfVG185KXOofhQYf8K2bvNyF6fN046zGqEMUCykpBIK3KHl6cwiMrmjNEA== Subject: Re: [PATCH -next] slimbus: qcom: fix potential NULL dereference in qcom_slim_prg_slew() To: Wei Yongjun , Sagar Dharia Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org References: <1526989582-139939-1-git-send-email-weiyongjun1@huawei.com> From: Srinivas Kandagatla Message-ID: <5b5c4eb4-0d13-7fa4-c0b6-e9949af4e1e1@linaro.org> Date: Wed, 23 May 2018 14:42:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <1526989582-139939-1-git-send-email-weiyongjun1@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/05/18 12:46, Wei Yongjun wrote: > platform_get_resource() may fail and return NULL, so we should > better check it's return value to avoid a NULL pointer dereference > a bit later in the code. > > This is detected by Coccinelle semantic patch. > > @@ > expression pdev, res, n, t, e, e1, e2; > @@ > > res = platform_get_resource_byname(pdev, t, n); > + if (!res) > + return -EINVAL; > ... when != res == NULL > e = devm_ioremap(e1, res->start, e2); > > Fixes: ad7fcbc308b0 ("slimbus: qcom: Add Qualcomm Slimbus controller driver") > Signed-off-by: Wei Yongjun > --- > drivers/slimbus/qcom-ctrl.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/slimbus/qcom-ctrl.c b/drivers/slimbus/qcom-ctrl.c > index bb36a8f..caea3b9 100644 > --- a/drivers/slimbus/qcom-ctrl.c > +++ b/drivers/slimbus/qcom-ctrl.c > @@ -478,6 +478,8 @@ static void qcom_slim_prg_slew(struct platform_device *pdev, > /* SLEW RATE register for this SLIMbus */ > slew_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM, > "slew"); > + if (!slew_mem) > + return; I think a better fix would be to do a devm_ioremap_resource() instead of devm_ioremap, which already has this check. This will also be inline with other resource handled in this driver. thanks, srini > ctrl->slew_reg = devm_ioremap(&pdev->dev, slew_mem->start, > resource_size(slew_mem)); > if (!ctrl->slew_reg) >