linux-kernel - [PATCH 4.9 04/21] crypto: pcrypt

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Date:   Mon,  8 Jan 2018 13:59:24 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, syzbot <syzkaller@...glegroups.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH 4.9 04/21] crypto: pcrypt - fix freeing pcrypt instances

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@...gle.com>

commit d76c68109f37cb85b243a1cf0f40313afd2bae68 upstream.

pcrypt is using the old way of freeing instances, where the ->free()
method specified in the 'struct crypto_template' is passed a pointer to
the 'struct crypto_instance'.  But the crypto_instance is being
kfree()'d directly, which is incorrect because the memory was actually
allocated as an aead_instance, which contains the crypto_instance at a
nonzero offset.  Thus, the wrong pointer was being kfree()'d.

Fix it by switching to the new way to free aead_instance's where the
->free() method is specified in the aead_instance itself.

Reported-by: syzbot <syzkaller@...glegroups.com>
Fixes: 0496f56065e0 ("crypto: pcrypt - Add support for new AEAD interface")
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 crypto/pcrypt.c |   19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

--- a/crypto/pcrypt.c
+++ b/crypto/pcrypt.c
@@ -254,6 +254,14 @@ static void pcrypt_aead_exit_tfm(struct
 	crypto_free_aead(ctx->child);
 }
 
+static void pcrypt_free(struct aead_instance *inst)
+{
+	struct pcrypt_instance_ctx *ctx = aead_instance_ctx(inst);
+
+	crypto_drop_aead(&ctx->spawn);
+	kfree(inst);
+}
+
 static int pcrypt_init_instance(struct crypto_instance *inst,
 				struct crypto_alg *alg)
 {
@@ -319,6 +327,8 @@ static int pcrypt_create_aead(struct cry
 	inst->alg.encrypt = pcrypt_aead_encrypt;
 	inst->alg.decrypt = pcrypt_aead_decrypt;
 
+	inst->free = pcrypt_free;
+
 	err = aead_register_instance(tmpl, inst);
 	if (err)
 		goto out_drop_aead;
@@ -349,14 +359,6 @@ static int pcrypt_create(struct crypto_t
 	return -EINVAL;
 }
 
-static void pcrypt_free(struct crypto_instance *inst)
-{
-	struct pcrypt_instance_ctx *ctx = crypto_instance_ctx(inst);
-
-	crypto_drop_aead(&ctx->spawn);
-	kfree(inst);
-}
-
 static int pcrypt_cpumask_change_notify(struct notifier_block *self,
 					unsigned long val, void *data)
 {
@@ -469,7 +471,6 @@ static void pcrypt_fini_padata(struct pa
 static struct crypto_template pcrypt_tmpl = {
 	.name = "pcrypt",
 	.create = pcrypt_create,
-	.free = pcrypt_free,
 	.module = THIS_MODULE,
 };