From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932173Ab2GFR0d (ORCPT ); Fri, 6 Jul 2012 13:26:33 -0400 Received: from fieldses.org ([174.143.236.118]:41833 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753031Ab2GFR0b (ORCPT ); Fri, 6 Jul 2012 13:26:31 -0400 Date: Fri, 6 Jul 2012 13:26:30 -0400 From: "J. Bruce Fields" To: Stanislav Kinsbursky 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 Message-ID: <20120706172630.GA11193@fieldses.org> References: <20120706134548.7307.1133.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120706134548.7307.1133.stgit@localhost.localdomain> 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 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? 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. --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; >