Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751306AbcDNTNN (ORCPT ); Thu, 14 Apr 2016 15:13:13 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:47901 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751080AbcDNTNM (ORCPT ); Thu, 14 Apr 2016 15:13:12 -0400 Date: Thu, 14 Apr 2016 22:12:53 +0300 From: Dan Carpenter To: "Gabriel L. Somlo" Cc: "Michael S. Tsirkin" , qemu-devel@nongnu.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [patch] firmware: qemu_fw_cfg.c: potential unintialized variable Message-ID: <20160414191253.GH4247@mwanda> References: <20160414093337.GD16549@mwanda> <20160414184005.GC7821@HEDWIG.INI.CMU.EDU> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160414184005.GC7821@HEDWIG.INI.CMU.EDU> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1033 Lines: 25 On Thu, Apr 14, 2016 at 02:40:06PM -0400, Gabriel L. Somlo wrote: > On Thu, Apr 14, 2016 at 12:33:37PM +0300, Dan Carpenter wrote: > > It acpi_acquire_global_lock() return AE_NOT_CONFIGURED then "glk" isn't > ^ ^ > If returns > > > initialized, which, if you got very unlucky, could cause a bug. > > > In principle I'm OK with being cautious and initializing local > variables just in case, but I'm curious: > > acpi_acquire_global_lock() (and its friend, acpi_release_global_lock()) > are both wrapped inside the same macro -- ACPI_HW_DEPENDENT_RETURN_STATUS > -- which either makes them both do something useful, or makes them both > no-ops returning a hardcoded AE_NOT_CONFIGURED. > > So what else do you think could be a way to get very unlucky ? If "glk" happened to to equal acpi_gbl_global_lock_handle by chance then we would release it without acquiring it first. Actually I could initialize it to zero and that would be better, no? regards, dan carpenter