linux-kernel - [PATCH 2.6.32 08/38] [PATCH 08/38] Initialize msg/shm IPC objects before doing ipc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20151129214703.212156285@1wt.eu>
Date:	Sun, 29 Nov 2015 22:47:10 +0100
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	Manfred Spraul <manfred@...orfullife.com>,
	Davidlohr Bueso <dbueso@...e.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ben Hutchings <ben@...adent.org.uk>, Willy Tarreau <w@....eu>
Subject: [PATCH 2.6.32 08/38] [PATCH 08/38] Initialize msg/shm IPC objects before doing
 ipc_addid()

2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

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 <dvyukov@...gle.com>
Cc: Manfred Spraul <manfred@...orfullife.com>
Cc: Davidlohr Bueso <dbueso@...e.de>
Cc: stable@...r.kernel.org
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
[bwh: Backported to 2.6.32:
 - Adjust context
 - The error path being moved looks a little different]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Willy Tarreau <w@....eu>
---
 ipc/msg.c  | 18 +++++++++---------
 ipc/shm.c  | 13 +++++++------
 ipc/util.c |  8 ++++----
 3 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/ipc/msg.c b/ipc/msg.c
index 779f762..94c6411 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -199,6 +199,15 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 		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
 	 */
@@ -209,15 +218,6 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 		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;
diff --git a/ipc/shm.c b/ipc/shm.c
index d30732c..75cb87c 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -386,12 +386,6 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 	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;
@@ -399,6 +393,13 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 	shp->shm_segsz = size;
 	shp->shm_nattch = 0;
 	shp->shm_file = file;
+
+	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.
diff --git a/ipc/util.c b/ipc/util.c
index 79ce84e..b6fe615 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -264,6 +264,10 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 	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, struct kern_ipc_perm* new, int size)
 
 	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;
-- 
1.7.12.2.21.g234cd45.dirty



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/