From 0bdf1e820160cdeb16cba1c5ea6892ae982a6587 Mon Sep 17 00:00:00 2001 From: Manfred Spraul Date: Tue, 2 Dec 2014 15:59:34 -0800 Subject: ipc/sem.c: fully initialize sem_array before making it visible commit e8577d1f0329d4842e8302e289fb2c22156abef4 upstream. ipc_addid() makes a new ipc identifier visible to everyone. New objects start as locked, so that the caller can complete the initialization after the call. Within struct sem_array, at least sma->sem_base and sma->sem_nsems are accessed without any locks, therefore this approach doesn't work. Thus: Move the ipc_addid() to the end of the initialization. Signed-off-by: Manfred Spraul Reported-by: Rik van Riel Acked-by: Rik van Riel Acked-by: Davidlohr Bueso Acked-by: Rafael Aquini Signed-off-by: Andrew Morton 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 --- ipc/sem.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/ipc/sem.c b/ipc/sem.c index 67f2110..b31c3ef 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -314,14 +314,6 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) return retval; } - id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); - if (id < 0) { - security_sem_free(sma); - ipc_rcu_putref(sma); - return id; - } - ns->used_sems += nsems; - sma->sem_base = (struct sem *) &sma[1]; for (i = 0; i < nsems; i++) @@ -332,6 +324,15 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) INIT_LIST_HEAD(&sma->list_id); sma->sem_nsems = nsems; sma->sem_ctime = get_seconds(); + + id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); + if (id < 0) { + security_sem_free(sma); + ipc_rcu_putref(sma); + return id; + } + ns->used_sems += nsems; + sem_unlock(sma); return sma->sem_perm.id; -- cgit v1.1