crypto: s390/aes - Fix buffer overread in CTR mode

[Herbert Xu <herbert@gondor.apana.org.au>]

When processing the last block, the s390 ctr code will always read
a whole block, even if there isn't a whole block of data left.  Fix
this by using the actual length left and copy it into a buffer first
for processing.

Fixes: 0200f3ecc196 ("crypto: s390 - add System z hardware support for CTR mode")
Cc: <stable@vger.kernel.org>
Reported-by: Guangwu Zhang <guazhang@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c
index c773820e4af9..c6fe5405de4a 100644
--- a/arch/s390/crypto/aes_s390.c
+++ b/arch/s390/crypto/aes_s390.c
@@ -597,7 +597,9 @@ static int ctr_aes_crypt(struct skcipher_request *req)
 	 * final block may be < AES_BLOCK_SIZE, copy only nbytes
 	 */
 	if (nbytes) {
-		cpacf_kmctr(sctx->fc, sctx->key, buf, walk.src.virt.addr,
+		memset(buf, 0, AES_BLOCK_SIZE);
+		memcpy(buf, walk.src.virt.addr, nbytes);
+		cpacf_kmctr(sctx->fc, sctx->key, buf, buf,
 			    AES_BLOCK_SIZE, walk.iv);
 		memcpy(walk.dst.virt.addr, buf, nbytes);
 		crypto_inc(walk.iv, AES_BLOCK_SIZE);
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt