[PATCH v2 6/6] crypto: algapi - enforce that all instances have a ->free() method

[Eric Biggers <ebiggers@kernel.org>]

From: Eric Biggers <ebiggers@google.com>

All instances need to have a ->free() method, but people could forget to
set it and then not notice if the instance is never unregistered.  To
help detect this bug earlier, don't allow an instance without a ->free()
method to be registered, and complain loudly if someone tries to do it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 crypto/aead.c     | 3 +++
 crypto/ahash.c    | 3 +++
 crypto/akcipher.c | 2 ++
 crypto/shash.c    | 3 +++
 crypto/skcipher.c | 3 +++
 5 files changed, 14 insertions(+)

diff --git a/crypto/aead.c b/crypto/aead.c
index 7707d3223101..16991095270d 100644
--- a/crypto/aead.c
+++ b/crypto/aead.c
@@ -288,6 +288,9 @@ int aead_register_instance(struct crypto_template *tmpl,
 {
 	int err;
 
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
+
 	err = aead_prepare_alg(&inst->alg);
 	if (err)
 		return err;
diff --git a/crypto/ahash.c b/crypto/ahash.c
index cd5d9847d513..68a0f0cb75c4 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -656,6 +656,9 @@ int ahash_register_instance(struct crypto_template *tmpl,
 {
 	int err;
 
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
+
 	err = ahash_prepare_alg(&inst->alg);
 	if (err)
 		return err;
diff --git a/crypto/akcipher.c b/crypto/akcipher.c
index eeed6c151d2f..f866085c8a4a 100644
--- a/crypto/akcipher.c
+++ b/crypto/akcipher.c
@@ -147,6 +147,8 @@ EXPORT_SYMBOL_GPL(crypto_unregister_akcipher);
 int akcipher_register_instance(struct crypto_template *tmpl,
 			       struct akcipher_instance *inst)
 {
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
 	akcipher_prepare_alg(&inst->alg);
 	return crypto_register_instance(tmpl, akcipher_crypto_instance(inst));
 }
diff --git a/crypto/shash.c b/crypto/shash.c
index 70faf28b2d14..c075b26c2a1d 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -577,6 +577,9 @@ int shash_register_instance(struct crypto_template *tmpl,
 {
 	int err;
 
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
+
 	err = shash_prepare_alg(&inst->alg);
 	if (err)
 		return err;
diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index 8c37243307aa..ba41f81fac0b 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -876,6 +876,9 @@ int skcipher_register_instance(struct crypto_template *tmpl,
 {
 	int err;
 
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
+
 	err = skcipher_prepare_alg(&inst->alg);
 	if (err)
 		return err;
-- 
2.24.1