From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751483Ab2GGF1e (ORCPT ); Sat, 7 Jul 2012 01:27:34 -0400 Received: from relay.parallels.com ([195.214.232.42]:41525 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082Ab2GGF1d convert rfc822-to-8bit (ORCPT ); Sat, 7 Jul 2012 01:27:33 -0400 Message-ID: <4FF7C8C2.8070203@parallels.com> Date: Sat, 7 Jul 2012 09:27:30 +0400 From: Stanislav Kinsbursky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 MIME-Version: 1.0 To: "J. Bruce Fields" CC: "linux-nfs@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devel@openvz.org" Subject: Re: [PATCH] [RFC] nfsd: fix possible dereference of static NULL nfsd_serv pointer References: <20120706134548.7307.1133.stgit@localhost.localdomain> <20120706172630.GA11193@fieldses.org> In-Reply-To: <20120706172630.GA11193@fieldses.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 06.07.2012 21:26, J. Bruce Fields пишет: > On Fri, Jul 06, 2012 at 05:45:56PM +0400, Stanislav Kinsbursky wrote: >> This is a bug fix for 3.5 kernel. >> In case on NFSd service start failure svc_shutdown_net() will call svc_destroy >> callback and zeroize global nfsd_serv pointer, this in turn will lead to Oops >> in svc_destroy(). >> >> This patch is marked as RFC, because to many lines were changed. It can be >> easely simplified if requested. >> Moreover, NFSd service shutdown is going to be converted into csomething on >> per-net basis. > Doesn't this leave error paths in e.g. __write_ports_addfd() and > __write_ports_addxprt() unfixed? Yes, sure it does... > I'm inclined to just submit your original fix (split up as in the last > version I sent) for 3.5 if you don't object. Not at all. Thanks, Bruce. > --b. > >> Signed-off-by: Stanislav Kinsbursky >> --- >> fs/nfsd/nfssvc.c | 14 ++++++++------ >> 1 files changed, 8 insertions(+), 6 deletions(-) >> >> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c >> index ee709fc..526a4aa 100644 >> --- a/fs/nfsd/nfssvc.c >> +++ b/fs/nfsd/nfssvc.c >> @@ -446,6 +446,7 @@ nfsd_svc(unsigned short port, int nrservs) >> int error; >> bool nfsd_up_before; >> struct net *net = &init_net; >> + struct svc_serv *serv = nfsd_serv; >> >> mutex_lock(&nfsd_mutex); >> dprintk("nfsd: creating service\n"); >> @@ -454,7 +455,7 @@ nfsd_svc(unsigned short port, int nrservs) >> if (nrservs > NFSD_MAXSERVS) >> nrservs = NFSD_MAXSERVS; >> error = 0; >> - if (nrservs == 0 && nfsd_serv == NULL) >> + if (nrservs == 0 && serv == NULL) >> goto out; >> >> error = nfsd_create_serv(); >> @@ -464,23 +465,24 @@ nfsd_svc(unsigned short port, int nrservs) >> nfsd_up_before = nfsd_up; >> >> error = nfsd_startup(port, nrservs); >> + error = -EINVAL; >> if (error) >> goto out_destroy; >> - error = svc_set_num_threads(nfsd_serv, NULL, nrservs); >> + error = svc_set_num_threads(serv, NULL, nrservs); >> if (error) >> goto out_shutdown; >> /* We are holding a reference to nfsd_serv which >> * we don't want to count in the return value, >> * so subtract 1 >> */ >> - error = nfsd_serv->sv_nrthreads - 1; >> + error = serv->sv_nrthreads - 1; >> out_shutdown: >> if (error < 0 && !nfsd_up_before) >> nfsd_shutdown(); >> out_destroy: >> - if (nfsd_serv->sv_nrthreads == 1) >> - svc_shutdown_net(nfsd_serv, net); >> - svc_destroy(nfsd_serv); /* Release server */ >> + if (serv->sv_nrthreads == 1) >> + svc_shutdown_net(serv, net); >> + svc_destroy(serv); /* Release server */ >> out: >> mutex_unlock(&nfsd_mutex); >> return error; >>