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    SubjectRe: [PATCH] cifs: Fix smbencrypt() to stop pointing a scatterlist at the stack
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    On Mon, 2016-12-12 at 12:54 -0800, Andy Lutomirski wrote:
    > 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>
    > ---
    >
    > Compile-tested only.
    >
    > fs/cifs/smbencrypt.c | 40 ++++++++--------------------------------
    > 1 file changed, 8 insertions(+), 32 deletions(-)
    >
    > diff --git a/fs/cifs/smbencrypt.c b/fs/cifs/smbencrypt.c
    > index 699b7868108f..c12bffefa3c9 100644
    > --- 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

    Acked-by: Jeff Layton <jlayton@redhat.com>

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