ipc: fix GETALL/IPC_RM race for sysv semaphores
We can step on WARN_ON_ONCE() in sem_getref() if a semaphore is removed
just as we are about to call sem_getref() from semctl_main(); results
are not pretty.
We should fail with -EIDRM, same as if IPC_RM happened while we'd been
doing allocation there. This also expands sem_getref() at its only
callsite (and fixed there), while sem_getref_and_unlock() is simply
killed off - it has no callers at all.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/ipc/sem.c b/ipc/sem.c
index e78ee31..4734e9c 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -328,28 +328,12 @@
ipc_rcu_putref(sma);
}
-static inline void sem_getref_and_unlock(struct sem_array *sma)
-{
- WARN_ON_ONCE(!ipc_rcu_getref(sma));
- sem_unlock(sma, -1);
-}
-
static inline void sem_putref(struct sem_array *sma)
{
sem_lock_and_putref(sma);
sem_unlock(sma, -1);
}
-/*
- * Call inside the rcu read section.
- */
-static inline void sem_getref(struct sem_array *sma)
-{
- sem_lock(sma, NULL, -1);
- WARN_ON_ONCE(!ipc_rcu_getref(sma));
- sem_unlock(sma, -1);
-}
-
static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
{
ipc_rmid(&sem_ids(ns), &s->sem_perm);
@@ -1116,9 +1100,14 @@
ushort __user *array = p;
int i;
+ sem_lock(sma, NULL, -1);
if(nsems > SEMMSL_FAST) {
- sem_getref(sma);
-
+ if (!ipc_rcu_getref(sma)) {
+ sem_unlock(sma, -1);
+ err = -EIDRM;
+ goto out_free;
+ }
+ sem_unlock(sma, -1);
sem_io = ipc_alloc(sizeof(ushort)*nsems);
if(sem_io == NULL) {
sem_putref(sma);
@@ -1131,9 +1120,7 @@
err = -EIDRM;
goto out_free;
}
- } else
- sem_lock(sma, NULL, -1);
-
+ }
for (i = 0; i < sma->sem_nsems; i++)
sem_io[i] = sma->sem_base[i].semval;
sem_unlock(sma, -1);
