From 561f8e2df990a7a2859a98bd208d0f7dc932c3f7 Mon Sep 17 00:00:00 2001
From: Tudor-Dan Ambarus <tudor.ambarus@microchip.com>
Date: Thu, 25 May 2017 10:18:12 +0300
Subject: [PATCH] crypto: akcipher - assume key is already set in maxsize
Git-commit: 561f8e2df990a7a2859a98bd208d0f7dc932c3f7
References: FATE#326323
Patch-mainline: v4.13

As of now, crypto_akcipher_maxsize() can not be reached without
successfully setting the key for the transformation. akcipher
algorithm implementations check if the key was set and then return
the output buffer size required for the given key.

Change the return type to unsigned int and always assume that this
function is called after a successful setkey of the transformation.
akcipher algorithm implementations will remove the check if key is not NULL
and directly return the max size.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 include/crypto/akcipher.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h
index c37cc59e9bf2..b5e11de4d497 100644
--- a/include/crypto/akcipher.h
+++ b/include/crypto/akcipher.h
@@ -98,7 +98,7 @@ struct akcipher_alg {
 			   unsigned int keylen);
 	int (*set_priv_key)(struct crypto_akcipher *tfm, const void *key,
 			    unsigned int keylen);
-	int (*max_size)(struct crypto_akcipher *tfm);
+	unsigned int (*max_size)(struct crypto_akcipher *tfm);
 	int (*init)(struct crypto_akcipher *tfm);
 	void (*exit)(struct crypto_akcipher *tfm);
 
@@ -257,13 +257,14 @@ static inline void akcipher_request_set_crypt(struct akcipher_request *req,
 /**
  * crypto_akcipher_maxsize() - Get len for output buffer
  *
- * Function returns the dest buffer size required for a given key
+ * Function returns the dest buffer size required for a given key.
+ * Function assumes that the key is already set in the transformation. If this
+ * function is called without a setkey or with a failed setkey, you will end up
+ * in a NULL dereference.
  *
  * @tfm:	AKCIPHER tfm handle allocated with crypto_alloc_akcipher()
- *
- * Return: minimum len for output buffer or error code in key hasn't been set
  */
-static inline int crypto_akcipher_maxsize(struct crypto_akcipher *tfm)
+static inline unsigned int crypto_akcipher_maxsize(struct crypto_akcipher *tfm)
 {
 	struct akcipher_alg *alg = crypto_akcipher_alg(tfm);
 
-- 
2.16.4