Commit 35cfc2b3 authored by Manfred Spraul's avatar Manfred Spraul Committed by Luis Henriques

ipc/sem.c: fully initialize sem_array before making it visible

commit e8577d1f 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: default avatarManfred Spraul <manfred@colorfullife.com>
Reported-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Acked-by: default avatarRafael Aquini <aquini@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 4e501862
......@@ -524,13 +524,6 @@ 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++) {
......@@ -545,6 +538,14 @@ 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();
......
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