cifs: Fix smbencrypt() to stop pointing a scatterlist at the stack

smbencrypt() points a scatterlist to the stack, which is breaks if
CONFIG_VMAP_STACK=y.

Fix it by switching to crypto_cipher_encrypt_one().  The new code
should be considerably faster as an added benefit.

This code is nearly identical to some code that Eric Biggers
suggested.

Cc: stable@vger.kernel.org # 4.9 only
Reported-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>

diff --git a/fs/cifs/smbencrypt.c b/fs/cifs/smbencrypt.c
index 699b7868108f658a3262943c7763b13d59767a89..c12bffefa3c9b59b2290ecdb243ae308b08e7224 100644 (file)
--- a/fs/cifs/smbencrypt.c
+++ b/fs/cifs/smbencrypt.c
@@ -23,7 +23,7 @@
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
 
-#include <crypto/skcipher.h>
+#include <linux/crypto.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
@@ -69,46 +69,22 @@ str_to_key(unsigned char *str, unsigned char *key)
 static int
 smbhash(unsigned char *out, const unsigned char *in, unsigned char *key)
 {
-       int rc;
        unsigned char key2[8];
-       struct crypto_skcipher *tfm_des;
-       struct scatterlist sgin, sgout;
-       struct skcipher_request *req;
+       struct crypto_cipher *tfm_des;
 
        str_to_key(key, key2);
 
-       tfm_des = crypto_alloc_skcipher("ecb(des)", 0, CRYPTO_ALG_ASYNC);
+       tfm_des = crypto_alloc_cipher("des", 0, 0);
        if (IS_ERR(tfm_des)) {
-               rc = PTR_ERR(tfm_des);
-               cifs_dbg(VFS, "could not allocate des crypto API\n");
-               goto smbhash_err;
-       }
-
-       req = skcipher_request_alloc(tfm_des, GFP_KERNEL);
-       if (!req) {
-               rc = -ENOMEM;
                cifs_dbg(VFS, "could not allocate des crypto API\n");
-               goto smbhash_free_skcipher;
+               return PTR_ERR(tfm_des);
        }
 
-       crypto_skcipher_setkey(tfm_des, key2, 8);
-
-       sg_init_one(&sgin, in, 8);
-       sg_init_one(&sgout, out, 8);
+       crypto_cipher_setkey(tfm_des, key2, 8);
+       crypto_cipher_encrypt_one(tfm_des, out, in);
+       crypto_free_cipher(tfm_des);
 
-       skcipher_request_set_callback(req, 0, NULL, NULL);
-       skcipher_request_set_crypt(req, &sgin, &sgout, 8, NULL);
-
-       rc = crypto_skcipher_encrypt(req);
-       if (rc)
-               cifs_dbg(VFS, "could not encrypt crypt key rc: %d\n", rc);
-
-       skcipher_request_free(req);
-
-smbhash_free_skcipher:
-       crypto_free_skcipher(tfm_des);
-smbhash_err:
-       return rc;
+       return 0;
 }
 
 static int