crypto: Unlink and free instances when deleted

We leak the crypto instance when we unregister an instance with
crypto_del_alg(). Therefore we introduce crypto_unregister_instance()
to unlink the crypto instance from the template's instances list and
to free the recources of the instance properly.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/algapi.c

@@ -518,6 +518,35 @@ int crypto_register_instance(struct crypto_template *tmpl,
 }
 EXPORT_SYMBOL_GPL(crypto_register_instance);
 
+int crypto_unregister_instance(struct crypto_alg *alg)
+{
+	int err;
+	struct crypto_instance *inst = (void *)alg;
+	struct crypto_template *tmpl = inst->tmpl;
+	LIST_HEAD(users);
+
+	if (!(alg->cra_flags & CRYPTO_ALG_INSTANCE))
+		return -EINVAL;
+
+	BUG_ON(atomic_read(&alg->cra_refcnt) != 1);
+
+	down_write(&crypto_alg_sem);
+
+	hlist_del_init(&inst->list);
+	err = crypto_remove_alg(alg, &users);
+
+	up_write(&crypto_alg_sem);
+
+	if (err)
+		return err;
+
+	tmpl->free(inst);
+	crypto_remove_final(&users);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_instance);
+
 int crypto_init_spawn(struct crypto_spawn *spawn, struct crypto_alg *alg,
 		      struct crypto_instance *inst, u32 mask)
 {

crypto/crypto_user.c

@@ -301,7 +301,7 @@ static int crypto_del_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (atomic_read(&alg->cra_refcnt) != 1)
 		return -EBUSY;
 
-	return crypto_unregister_alg(alg);
+	return crypto_unregister_instance(alg);
 }
 
 static int crypto_add_alg(struct sk_buff *skb, struct nlmsghdr *nlh,

include/crypto/algapi.h

@@ -134,6 +134,7 @@ struct crypto_template *crypto_lookup_template(const char *name);
 
 int crypto_register_instance(struct crypto_template *tmpl,
 			     struct crypto_instance *inst);
+int crypto_unregister_instance(struct crypto_alg *alg);
 
 int crypto_init_spawn(struct crypto_spawn *spawn, struct crypto_alg *alg,
 		      struct crypto_instance *inst, u32 mask);