Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763154Ab3ECKnl (ORCPT ); Fri, 3 May 2013 06:43:41 -0400 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:46628 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763140Ab3ECKni (ORCPT ); Fri, 3 May 2013 06:43:38 -0400 Date: Fri, 3 May 2013 12:42:08 +0200 From: Peter Zijlstra To: wangbiao Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@redhat.com, yanmin.zhang@intel.com, mochel@digitalimplant.org Subject: Re: [PATCH] klist: del waiter from klist_remove_waiters before wakeup waitting process Message-ID: <20130503104207.GA27558@dyad.programming.kicks-ass.net> References: <1367564796.27529.15.camel@wangbiao> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1367564796.27529.15.camel@wangbiao> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1653 Lines: 53 On Fri, May 03, 2013 at 03:06:36PM +0800, wangbiao wrote: > From: "wang, biao" > Date: Fri, 3 May 2013 14:18:34 +0800 > Subject: [PATCH] klist: del waiter from klist_remove_waiters before wakeup > waitting process > > There is a race between klist_remove and klist_release. klist_remove > uses a local var waiter saved on stack. When klist_release calls > wake_up_process(waiter->process) to wake up the waiter, waiter might run > immediately and reuse the stack. Then, klist_release calls > list_del(&waiter->list) to change previous > wait data and cause prior waiter thread corrupt. > > The patch fixes it against kernel 3.9. I've never seen that code before in my life; but after a quick look you appear to be completely right. > Signed-off-by: wang, biao Acked-by: Peter Zijlstra > --- > lib/klist.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/lib/klist.c b/lib/klist.c > index 0874e41..358a368 100644 > --- a/lib/klist.c > +++ b/lib/klist.c > @@ -193,10 +193,10 @@ static void klist_release(struct kref *kref) > if (waiter->node != n) > continue; > > + list_del(&waiter->list); > waiter->woken = 1; > mb(); > wake_up_process(waiter->process); > - list_del(&waiter->list); > } > spin_unlock(&klist_remove_lock); > knode_set_klist(n, NULL); > -- > 1.7.6 > > > -- 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/