Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757975Ab3CGUJI (ORCPT ); Thu, 7 Mar 2013 15:09:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:63177 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752698Ab3CGUJG (ORCPT ); Thu, 7 Mar 2013 15:09:06 -0500 Date: Thu, 7 Mar 2013 21:07:22 +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: <20130307200722.GA22072@redhat.com> References: <1361802350-9299-1-git-send-email-lucas.demarchi@profusion.mobi> <20130225160642.GA31806@redhat.com> <20130225180802.GA6160@redhat.com> <20130307193701.GA20385@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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: 1511 Lines: 43 On 03/07, Lucas De Marchi wrote: > > On Thu, Mar 7, 2013 at 4:37 PM, Oleg Nesterov wrote: > > > >> @@ -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. > > Even if it's killed, we would just free the resource we allocated > before. Yes, and after that ____call_usermodehelper() can do do_execve(module_name) ? > It would not be safe if we allocated in the init function and > freed in the cleanup. But we do? We free this memory in cleanup ? And I was allocated by us. sub_info itself can't go away (if you meant this), but sub_info->path/argv/envp can. > Or am I missing something? Or me... 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/