Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756737AbYAQTX7 (ORCPT ); Thu, 17 Jan 2008 14:23:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753841AbYAQTXv (ORCPT ); Thu, 17 Jan 2008 14:23:51 -0500 Received: from smtp2.linux-foundation.org ([207.189.120.14]:58983 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752281AbYAQTXu (ORCPT ); Thu, 17 Jan 2008 14:23:50 -0500 Date: Thu, 17 Jan 2008 11:23:32 -0800 From: Andrew Morton To: "Rafael J. Wysocki" Cc: nigel@nigel.suspend2.net, LKML , pm list , TuxOnIce-devel , Pavel Machek Subject: Re: [PATCH] (2.4.25 material?) Fix unbalanced helper_lock in kernel/kmod.c Message-Id: <20080117112332.9e34b7d9.akpm@linux-foundation.org> In-Reply-To: <200801171902.44133.rjw@sisk.pl> References: <478EA17B.30601@nigel.suspend2.net> <200801171902.44133.rjw@sisk.pl> X-Mailer: Sylpheed 2.4.1 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3095 Lines: 106 On Thu, 17 Jan 2008 19:02:43 +0100 "Rafael J. Wysocki" wrote: > On Thursday, 17 of January 2008, Nigel Cunningham wrote: > > Hi all. > > Hi, > > > First up, sorry for not inlining the patch - trouble with line wrapping. > > No big deal. > > > In 2.6.24-rc8, call_usermodehelper_exec has an exit path that can leave > > the helper_lock() call at the top of the routine unbalanced. The > > attached patch fixes this issue. > > Thanks a lot for the patch (reproduced below), I think it's 2.6.24 material. > Andrew? > > > Signed-off-by: Nigel Cunningham > > --- > From: Nigel Cunningham > > In 2.6.24-rc8, call_usermodehelper_exec has an exit path that can leave > the helper_lock() call at the top of the routine unbalanced. Fix it. > > Signed-off-by: Nigel Cunningham > Signed-off-by: Rafael J. Wysocki > --- > diff --git a/kernel/kmod.c b/kernel/kmod.c > index c6a4f8a..de27e15 100644 > --- a/kernel/kmod.c > +++ b/kernel/kmod.c > @@ -468,8 +468,10 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, > sub_info->wait = wait; > > queue_work(khelper_wq, &sub_info->work); > - if (wait == UMH_NO_WAIT) /* task has freed sub_info */ > + if (wait == UMH_NO_WAIT) { /* task has freed sub_info */ > + helper_unlock(); > return 0; > + } > wait_for_completion(&done); > retval = sub_info->retval; > Yup, I ended up queueing this: From: Nigel Cunningham call_usermodehelper_exec() has an exit path that can leave the helper_lock() call at the top of the routine unbalanced. The attached patch fixes this issue. Signed-off-by: Nigel Cunningham Cc: Signed-off-by: Andrew Morton --- kernel/kmod.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff -puN kernel/kmod.c~fix-unbalanced-helper_lock-in-kernel-kmodc kernel/kmod.c --- a/kernel/kmod.c~fix-unbalanced-helper_lock-in-kernel-kmodc +++ a/kernel/kmod.c @@ -451,13 +451,11 @@ int call_usermodehelper_exec(struct subp enum umh_wait wait) { DECLARE_COMPLETION_ONSTACK(done); - int retval; + int retval = 0; helper_lock(); - if (sub_info->path[0] == '\0') { - retval = 0; + if (sub_info->path[0] == '\0') goto out; - } if (!khelper_wq || usermodehelper_disabled) { retval = -EBUSY; @@ -468,13 +466,14 @@ int call_usermodehelper_exec(struct subp sub_info->wait = wait; queue_work(khelper_wq, &sub_info->work); - if (wait == UMH_NO_WAIT) /* task has freed sub_info */ - return 0; + if (wait == UMH_NO_WAIT) /* task has freed sub_info */ + goto unlock; wait_for_completion(&done); retval = sub_info->retval; - out: +out: call_usermodehelper_freeinfo(sub_info); +unlock: helper_unlock(); return retval; } _ -- 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/