From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753037Ab2GFNtv (ORCPT ); Fri, 6 Jul 2012 09:49:51 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:47109 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752050Ab2GFNtt (ORCPT ); Fri, 6 Jul 2012 09:49:49 -0400 Subject: [PATCH] [RFC] nfsd: fix possible dereference of static NULL nfsd_serv pointer To: bfields@fieldses.org From: Stanislav Kinsbursky Cc: linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, devel@openvz.org Date: Fri, 06 Jul 2012 17:45:56 +0400 Message-ID: <20120706134548.7307.1133.stgit@localhost.localdomain> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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;