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SubjectRe: [PATCH] cifs: Fix smbencrypt() to stop pointing a scatterlist at the stack
merged into cifs-2.6.git for-next

On Tue, Dec 13, 2016 at 7:07 AM, Jeff Layton <jlayton@redhat.com> wrote:
> 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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--
Thanks,

Steve

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