keys: sparse: Fix incorrect RCU accesses

Fix a pair of accesses that should be using RCU protection.

rcu_dereference_protected() is needed to access task_struct::real_parent.

current_cred() should be used to access current->cred.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>

security/keys/keyctl.c

@@ -1524,7 +1524,8 @@ long keyctl_session_to_parent(void)
 
 	ret = -EPERM;
 	oldwork = NULL;
-	parent = me->real_parent;
+	parent = rcu_dereference_protected(me->real_parent,
+					   lockdep_is_held(&tasklist_lock));
 
 	/* the parent mustn't be init and mustn't be a kernel thread */
 	if (parent->pid <= 1 || !parent->mm)

security/keys/request_key_auth.c

@@ -152,7 +152,7 @@ struct key *request_key_auth_new(struct key *target, const char *op,
 				 struct key *dest_keyring)
 {
 	struct request_key_auth *rka, *irka;
-	const struct cred *cred = current->cred;
+	const struct cred *cred = current_cred();
 	struct key *authkey = NULL;
 	char desc[20];
 	int ret = -ENOMEM;