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authorManfred Spraul <manfred@colorfullife.com>2014-12-02 15:59:34 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-03 09:36:03 -0800
commite8577d1f0329d4842e8302e289fb2c22156abef4 (patch)
treef16f344a3d414db2a0d848b7ca19470b468c902e
parent92788ac1eb06e69a822de45e2a8a63fa45eb5be2 (diff)
downloadlinux-linaro-stable-e8577d1f0329d4842e8302e289fb2c22156abef4.tar.gz
ipc/sem.c: fully initialize sem_array before making it visible
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 <manfred@colorfullife.com> Reported-by: Rik van Riel <riel@redhat.com> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--ipc/sem.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index 454f6c6020a8..53c3310f41c6 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -507,13 +507,6 @@ 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) {
- ipc_rcu_putref(sma, sem_rcu_free);
- return id;
- }
- ns->used_sems += nsems;
-
sma->sem_base = (struct sem *) &sma[1];
for (i = 0; i < nsems; i++) {
@@ -528,6 +521,14 @@ 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) {
+ ipc_rcu_putref(sma, sem_rcu_free);
+ return id;
+ }
+ ns->used_sems += nsems;
+
sem_unlock(sma, -1);
rcu_read_unlock();