releases/5.0.14/net-hns-fix-kasan-use-after-free-in-hns_nic_net_xmit.patch

From 2435e8fe1e577c8c75e9c93a0605ad06ee58488c Mon Sep 17 00:00:00 2001
From: Liubin Shu <shuliubin@huawei.com>
Date: Thu, 4 Apr 2019 16:46:42 +0800
Subject: net: hns: fix KASAN: use-after-free in hns_nic_net_xmit_hw()

[ Upstream commit 3a39a12ad364a9acd1038ba8da67cd8430f30de4 ]

This patch is trying to fix the issue due to:
[27237.844750] BUG: KASAN: use-after-free in hns_nic_net_xmit_hw+0x708/0xa18[hns_enet_drv]

After hnae_queue_xmit() in hns_nic_net_xmit_hw(), can be
interrupted by interruptions, and than call hns_nic_tx_poll_one()
to handle the new packets, and free the skb. So, when turn back to
hns_nic_net_xmit_hw(), calling skb->len will cause use-after-free.

This patch update tx ring statistics in hns_nic_tx_poll_one() to
fix the bug.

Signed-off-by: Liubin Shu <shuliubin@huawei.com>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
---
 drivers/net/ethernet/hisilicon/hns/hns_enet.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns/hns_enet.c b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
index 60e7d7ae3787..e5a7c0761dbd 100644
--- a/drivers/net/ethernet/hisilicon/hns/hns_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns/hns_enet.c
@@ -376,8 +376,6 @@ netdev_tx_t hns_nic_net_xmit_hw(struct net_device *ndev,
 	wmb(); /* commit all data before submit */
 	assert(skb->queue_mapping < priv->ae_handle->q_num);
 	hnae_queue_xmit(priv->ae_handle->qs[skb->queue_mapping], buf_num);
-	ring->stats.tx_pkts++;
-	ring->stats.tx_bytes += skb->len;
 
 	return NETDEV_TX_OK;
 
@@ -999,6 +997,9 @@ static int hns_nic_tx_poll_one(struct hns_nic_ring_data *ring_data,
 		/* issue prefetch for next Tx descriptor */
 		prefetch(&ring->desc_cb[ring->next_to_clean]);
 	}
+	/* update tx ring statistics. */
+	ring->stats.tx_pkts += pkts;
+	ring->stats.tx_bytes += bytes;
 
 	NETIF_TX_UNLOCK(ring);
 
-- 
2.20.1