From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755213AbZKDK3P (ORCPT ); Wed, 4 Nov 2009 05:29:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754403AbZKDK3P (ORCPT ); Wed, 4 Nov 2009 05:29:15 -0500 Received: from gw1.cosmosbay.com ([212.99.114.194]:40487 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752503AbZKDK3O (ORCPT ); Wed, 4 Nov 2009 05:29:14 -0500 Message-ID: <4AF15771.8060204@gmail.com> Date: Wed, 04 Nov 2009 11:29:05 +0100 From: Eric Dumazet User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: Amerigo Wang CC: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, "David S. Miller" Subject: Re: [Patch] net: fix incorrect counting in __scm_destroy() References: <20091104100717.4785.57149.sendpatchset@localhost.localdomain> In-Reply-To: <20091104100717.4785.57149.sendpatchset@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-1.6 (gw1.cosmosbay.com [0.0.0.0]); Wed, 04 Nov 2009 11:29:05 +0100 (CET) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Amerigo Wang a écrit : > It seems that in __scm_destroy() we forgot to decrease > the ->count after fput(->fp[i]), this may cause some > problem when we recursively call fput() again. > > Signed-off-by: WANG Cong > Cc: David S. Miller > > --- > diff --git a/net/core/scm.c b/net/core/scm.c > index b7ba91b..fa53219 100644 > --- a/net/core/scm.c > +++ b/net/core/scm.c > @@ -120,8 +120,10 @@ void __scm_destroy(struct scm_cookie *scm) > fpl = list_first_entry(&work_list, struct scm_fp_list, list); > > list_del(&fpl->list); > - for (i=fpl->count-1; i>=0; i--) > + for (i = fpl->count-1; i >= 0; i--) { > fput(fpl->fp[i]); > + fpl->count--; > + } > kfree(fpl); > } > Hmm, your patch seems suspicious. Are you fixing a real crash/bug, or is it something you discovered in a code review ? Given we kfree(fpl) at the end of loop, we cannot recursively call __scm_destroy() on same fpl, it would be a bug anyway ? So you probably need something better, like testing fpl->list being not re-included in current->scm_work_list before kfree() it