From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752265AbeBBQaT (ORCPT ); Fri, 2 Feb 2018 11:30:19 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:56480 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751963AbeBBQaK (ORCPT ); Fri, 2 Feb 2018 11:30:10 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 7735B60364 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=jcrouse@codeaurora.org Date: Fri, 2 Feb 2018 09:30:06 -0700 From: Jordan Crouse To: "Gustavo A. R. Silva" Cc: Rob Clark , David Airlie , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/msm/adreno/a5xx_debugfs: fix potential NULL pointer dereference Message-ID: <20180202163006.GA878@jcrouse-lnx.qualcomm.com> Mail-Followup-To: "Gustavo A. R. Silva" , Rob Clark , David Airlie , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20180202123223.GA4410@embeddedor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180202123223.GA4410@embeddedor.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 02, 2018 at 06:32:23AM -0600, Gustavo A. R. Silva wrote: > _minor_ is being dereferenced before it is null checked, hence there > is a potential null pointer dereference. Fix this by moving the pointer > dereference after _minor_ has been null checked. > > Fixes: 024ad8df763f ("drm/msm: add a5xx specific debugfs") > Signed-off-by: Gustavo A. R. Silva > --- > > I wonder if a better solution for this would be to WARN_ON in case _minor_ > happens to be NULL and return -EINVAL, instead of just returning zero. > > Something like: > > struct drm_device *dev; > > if (WARN_ON(!minor) > return -EINVAL; > > dev = minor->dev; > > What do you think? In my opinion everything in debugfs is optional. I'm not sure if it is even possible for dev->primary, dev->render or dev->control to be NULL from the DRM core but if so I think the failure should be silent. Jordan > > drivers/gpu/drm/msm/adreno/a5xx_debugfs.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c b/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c > index 6b27941..059ec7d 100644 > --- a/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c > +++ b/drivers/gpu/drm/msm/adreno/a5xx_debugfs.c > @@ -159,13 +159,15 @@ DEFINE_SIMPLE_ATTRIBUTE(reset_fops, NULL, reset_set, "%llx\n"); > > int a5xx_debugfs_init(struct msm_gpu *gpu, struct drm_minor *minor) > { > - struct drm_device *dev = minor->dev; > + struct drm_device *dev; > struct dentry *ent; > int ret; > > if (!minor) > return 0; > > + dev = minor->dev; > + > ret = drm_debugfs_create_files(a5xx_debugfs_list, > ARRAY_SIZE(a5xx_debugfs_list), > minor->debugfs_root, minor); > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project