cred: add missing return error code when set_cred_ucounts() failed

If set_cred_ucounts() failed, we need return the error code.

Fixes: 905ae01c ("Add a reference to ucounts for each cred")
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Link: https://lkml.kernel.org/r/20210526143805.2549649-1-yangyingliang@huawei.comReviewed-by: NAlexey Gladkov <legion@kernel.org>
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

kernel/cred.c

@@ -372,7 +372,8 @@ int copy_creds(struct task_struct *p, unsigned long clone_flags)
 		ret = create_user_ns(new);
 		if (ret < 0)
 			goto error_put;
-		if (set_cred_ucounts(new) < 0)
+		ret = set_cred_ucounts(new);
+		if (ret < 0)
 			goto error_put;
 	}