From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752438Ab3LYVxA (ORCPT ); Wed, 25 Dec 2013 16:53:00 -0500 Received: from mail.fireflyinternet.com ([87.106.93.118]:50648 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752199Ab3LYVw6 (ORCPT ); Wed, 25 Dec 2013 16:52:58 -0500 X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.73.22; Date: Wed, 25 Dec 2013 21:52:49 +0000 From: Chris Wilson To: Tetsuo Handa Cc: ben@bwidawsk.net, daniel.vetter@ffwll.ch, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/i915: Fix refcount leak and possible NULL pointer dereference. Message-ID: <20131225215249.GA3832@nuc-i3427.alporthouse.com> References: <201312242050.CGH78112.JQFOSVMLOFtHOF@I-love.SAKURA.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201312242050.CGH78112.JQFOSVMLOFtHOF@I-love.SAKURA.ne.jp> 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 Tue, Dec 24, 2013 at 08:50:23PM +0900, Tetsuo Handa wrote: > >From 482be6384379072eb4c0d45d0ab8a25df4f59ed7 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa > Date: Tue, 24 Dec 2013 18:04:14 +0900 > Subject: [PATCH] drm/i915: Fix refcount leak and possible NULL pointer dereference. > > Since get_pid_task() grabs a reference on the task_struct, we have to drop the > refcount after reading that task's comm name. Also, directly reading like > get_pid_task()->comm can trigger an oops when get_pid_task() returned NULL. The second issue is moot as file itself cannot exist if the task_struct is NULL, and the task_struct cannot be destroyed until we finish the function. The simpler fix would appear to be s/get_pid_task/pid_task/ -Chris -- Chris Wilson, Intel Open Source Technology Centre