netdev - [PATCH net-next] net: ena: fix unintended sign extension

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Date:   Fri, 12 Oct 2018 21:49:48 +0200
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Netanel Belgazal <netanel@...zon.com>,
        Saeed Bishara <saeedb@...zon.com>,
        Zorik Machulsky <zorik@...zon.com>,
        "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH net-next] net: ena: fix unintended sign extension

In the following expression:

372                size = io_sq->bounce_buf_ctrl.buffer_size *
373                         io_sq->bounce_buf_ctrl.buffers_num;

both buffer_size and buffers_num are of type u16 (16 bits, unsigned),
so they are promoted to type int (32 bits, signed) and then
sign-extended to type size_t.

Fix this by casting io_sq->bounce_buf_ctrl.buffer_size to size_t in
order to avoid the sign extension and unintended results.

Addresses-Coverity-ID: 1474187 ("Unintended sign extension")
Addresses-Coverity-ID: 1474189 ("Unintended sign extension")
Fixes: 689b2bdaaa14 ("net: ena: add functions for handling Low Latency Queues in ena_com")
Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 drivers/net/ethernet/amazon/ena/ena_com.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index 420cede..9a8130e 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -369,7 +369,7 @@ static int ena_com_init_io_sq(struct ena_com_dev *ena_dev,
 			ENA_COM_BOUNCE_BUFFER_CNTRL_CNT;
 		io_sq->bounce_buf_ctrl.next_to_use = 0;
 
-		size = io_sq->bounce_buf_ctrl.buffer_size *
+		size = (size_t)io_sq->bounce_buf_ctrl.buffer_size *
 			 io_sq->bounce_buf_ctrl.buffers_num;
 
 		dev_node = dev_to_node(ena_dev->dmadev);
-- 
2.7.4