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

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: 0200f3ec ("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>
Reviewd-by: Harald Freudenberger <freude@de.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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);

arch/s390/crypto/paes_s390.c

@@ -693,9 +693,11 @@ static int ctr_paes_crypt(struct skcipher_request *req)
 	 * final block may be < AES_BLOCK_SIZE, copy only nbytes
 	 */
 	if (nbytes) {
+		memset(buf, 0, AES_BLOCK_SIZE);
+		memcpy(buf, walk.src.virt.addr, nbytes);
 		while (1) {
 			if (cpacf_kmctr(ctx->fc, &param, buf,
-					walk.src.virt.addr, AES_BLOCK_SIZE,
+					buf, AES_BLOCK_SIZE,
 					walk.iv) == AES_BLOCK_SIZE)
 				break;
 			if (__paes_convert_key(ctx))