apparmor: aa_label_alloc use aa_label_free on alloc failure

aa_label_alloc() allocates a secid before allocating or taking the label
proxy. If the later proxy step fails, the error path only freed the label
memory, leaking any resources initialized by aa_label_init().

Use aa_label_free() on the failure path so partially initialized labels
release their secid and other label resources before the backing memory is
freed.

Fixes: f1bd904175 ("apparmor: add the base fns() for domain labels")
Signed-off-by: Zygmunt Krynicki <me@zygoon.pl>
Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/label.c

@@ -458,7 +458,7 @@ struct aa_label *aa_label_alloc(int size, struct aa_proxy *proxy, gfp_t gfp)
 	return new;
 
 fail:
-	kfree(new);
+	aa_label_free(new);
 
 	return NULL;
 }