From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934714AbbJIAjp (ORCPT ); Thu, 8 Oct 2015 20:39:45 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35833 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934689AbbJIAjl (ORCPT ); Thu, 8 Oct 2015 20:39:41 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Manfred Spraul" , "Dmitry Vyukov" , stable@vger.kernel.org, "Davidlohr Bueso" , "Linus Torvalds" Date: Fri, 09 Oct 2015 01:12:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 094/107] Initialize msg/shm IPC objects before doing ipc_addid() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.247 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.72-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Linus Torvalds commit b9a532277938798b53178d5a66af6e2915cb27cf upstream. As reported by Dmitry Vyukov, we really shouldn't do ipc_addid() before having initialized the IPC object state. Yes, we initialize the IPC object in a locked state, but with all the lockless RCU lookup work, that IPC object lock no longer means that the state cannot be seen. We already did this for the IPC semaphore code (see commit e8577d1f0329: "ipc/sem.c: fully initialize sem_array before making it visible") but we clearly forgot about msg and shm. Reported-by: Dmitry Vyukov Cc: Manfred Spraul Cc: Davidlohr Bueso Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: - Adjust context - The error path being moved looks a little different] Signed-off-by: Ben Hutchings --- --- a/ipc/msg.c +++ b/ipc/msg.c @@ -198,6 +198,15 @@ static int newque(struct ipc_namespace * return retval; } + msq->q_stime = msq->q_rtime = 0; + msq->q_ctime = get_seconds(); + msq->q_cbytes = msq->q_qnum = 0; + msq->q_qbytes = ns->msg_ctlmnb; + msq->q_lspid = msq->q_lrpid = 0; + INIT_LIST_HEAD(&msq->q_messages); + INIT_LIST_HEAD(&msq->q_receivers); + INIT_LIST_HEAD(&msq->q_senders); + /* * ipc_addid() locks msq */ @@ -208,15 +217,6 @@ static int newque(struct ipc_namespace * return id; } - msq->q_stime = msq->q_rtime = 0; - msq->q_ctime = get_seconds(); - msq->q_cbytes = msq->q_qnum = 0; - msq->q_qbytes = ns->msg_ctlmnb; - msq->q_lspid = msq->q_lrpid = 0; - INIT_LIST_HEAD(&msq->q_messages); - INIT_LIST_HEAD(&msq->q_receivers); - INIT_LIST_HEAD(&msq->q_senders); - msg_unlock(msq); return msq->q_perm.id; --- a/ipc/shm.c +++ b/ipc/shm.c @@ -498,12 +498,6 @@ static int newseg(struct ipc_namespace * if (IS_ERR(file)) goto no_file; - id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); - if (id < 0) { - error = id; - goto no_id; - } - shp->shm_cprid = task_tgid_vnr(current); shp->shm_lprid = 0; shp->shm_atim = shp->shm_dtim = 0; @@ -512,6 +506,13 @@ static int newseg(struct ipc_namespace * shp->shm_nattch = 0; shp->shm_file = file; shp->shm_creator = current; + + id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); + if (id < 0) { + error = id; + goto no_id; + } + /* * shmid gets reported as "inode#" in /proc/pid/maps. * proc-ps tools use this. Changing this will break them. --- a/ipc/util.c +++ b/ipc/util.c @@ -264,6 +264,10 @@ int ipc_addid(struct ipc_ids* ids, struc rcu_read_lock(); spin_lock(&new->lock); + current_euid_egid(&euid, &egid); + new->cuid = new->uid = euid; + new->gid = new->cgid = egid; + err = idr_get_new(&ids->ipcs_idr, new, &id); if (err) { spin_unlock(&new->lock); @@ -273,10 +277,6 @@ int ipc_addid(struct ipc_ids* ids, struc ids->in_use++; - current_euid_egid(&euid, &egid); - new->cuid = new->uid = euid; - new->gid = new->cgid = egid; - new->seq = ids->seq++; if(ids->seq > ids->seq_max) ids->seq = 0;