crypto: fix a memory leak in rsa-kcs1pad's encryption mode

mainline inclusion
from mainline-4.20-rc1
commit 3944f139d5592790b70bc64f197162e643a8512b
category: bugfix
bugzilla: 6250
CVE: NA

---------------------------

The encryption mode of pkcs1pad never uses out_sg and out_buf, so
there's no need to allocate the buffer, which presently is not even
being freed.

CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: linux-crypto@vger.kernel.org
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NDan Aloni <dan@kernelim.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NJason Yan <yanaijie@huawei.com>
Reviewed-by: NZhang xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

crypto/rsa-pkcs1pad.c

@@ -261,15 +261,6 @@ static int pkcs1pad_encrypt(struct akcipher_request *req)
 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
 			ctx->key_size - 1 - req->src_len, req->src);
 
-	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
-	if (!req_ctx->out_buf) {
-		kfree(req_ctx->in_buf);
-		return -ENOMEM;
-	}
-
-	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
-			ctx->key_size, NULL);
-
 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
 			pkcs1pad_encrypt_sign_complete_cb, req);