Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933361Ab3CGTir (ORCPT ); Thu, 7 Mar 2013 14:38:47 -0500 Received: from mx1.redhat.com ([209.132.183.28]:22529 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932724Ab3CGTiq (ORCPT ); Thu, 7 Mar 2013 14:38:46 -0500 Date: Thu, 7 Mar 2013 20:37:01 +0100 From: Oleg Nesterov To: Lucas De Marchi Cc: linux-kernel@vger.kernel.org, David Howells , James Morris , Andrew Morton Subject: Re: [PATCH] usermodehelper: Fix -ENOMEM return logic Message-ID: <20130307193701.GA20385@redhat.com> References: <1361802350-9299-1-git-send-email-lucas.demarchi@profusion.mobi> <20130225160642.GA31806@redhat.com> <20130225180802.GA6160@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1430 Lines: 39 Hi Lucas, On 03/06, Lucas De Marchi wrote: > > On Mon, Feb 25, 2013 at 3:08 PM, Oleg Nesterov wrote: > > > > So, I hope you will send v2. I'd suggest to split the fixes. 1/3 > > should create/export the new helpers, and 2-3 fix should call_modprobe() > > and call_usermodehelper_keys(). But this is up to you, I won't insist. > > I was implementing this today, but looking into call_modprobe(), it is > never called with UMH_NO_WAIT. wait == T means UMH_WAIT_PROC, so we can't simply rely on CLONE_VFORK. But probably we can rely on sys_wait4. However, > @@ -98,12 +93,13 @@ static int call_modprobe(char *module_name, int wait) > ? argv[3] = module_name; /* check free_modprobe_argv() */ > ? argv[4] = NULL; > > - return call_usermodehelper_fns(modprobe_path, argv, envp, > - wait | UMH_KILLABLE, NULL, free_modprobe_argv, NULL); > + ret = call_usermodehelper(modprobe_path, argv, envp, > + ?wait | UMH_KILLABLE); > + kfree(module_name); Please note UMH_KILLABLE. call_usermodehelper() can be interrupted and even UMH_WAIT_EXEC case is not safe. If call_modprobe() is killed we can return while the workqueue thread still tries to clone/exec/etc. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/