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From:   Huazhong Tan <tanhuazhong@huawei.com>
To:     <davem@davemloft.net>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <salil.mehta@huawei.com>, <yisen.zhuang@huawei.com>,
        <linuxarm@huawei.com>, <kuba@kernel.org>,
        Yunsheng Lin <linyunsheng@huawei.com>,
        Huazhong Tan <tanhuazhong@huawei.com>
Subject: [PATCH net 1/5] net: hns3: fix desc filling bug when skb is expanded or lineared
Date:   Tue, 28 Jul 2020 10:16:48 +0800
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From: Yunsheng Lin <linyunsheng@huawei.com>

The linear and frag data part may be changed when the skb is expanded
or lineared in skb_cow_head() or skb_checksum_help(), which is called
by hns3_fill_skb_desc(), so the linear len return by skb_headlen()
before the calling of hns3_fill_skb_desc() is unreliable.

Move hns3_fill_skb_desc() before the calling of skb_headlen() to fix
this bug.

Fixes: 76ad4f0ee747 ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
---
 drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 33c481d..3328500 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -1093,16 +1093,8 @@ static int hns3_fill_desc(struct hns3_enet_ring *ring, void *priv,
 	int k, sizeoflast;
 	dma_addr_t dma;
 
-	if (type == DESC_TYPE_SKB) {
-		struct sk_buff *skb = (struct sk_buff *)priv;
-		int ret;
-
-		ret = hns3_fill_skb_desc(ring, skb, desc);
-		if (unlikely(ret < 0))
-			return ret;
-
-		dma = dma_map_single(dev, skb->data, size, DMA_TO_DEVICE);
-	} else if (type == DESC_TYPE_FRAGLIST_SKB) {
+	if (type == DESC_TYPE_FRAGLIST_SKB ||
+	    type == DESC_TYPE_SKB) {
 		struct sk_buff *skb = (struct sk_buff *)priv;
 
 		dma = dma_map_single(dev, skb->data, size, DMA_TO_DEVICE);
@@ -1439,6 +1431,10 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 
 	next_to_use_head = ring->next_to_use;
 
+	ret = hns3_fill_skb_desc(ring, skb, &ring->desc[ring->next_to_use]);
+	if (unlikely(ret < 0))
+		goto fill_err;
+
 	ret = hns3_fill_skb_to_desc(ring, skb, DESC_TYPE_SKB);
 	if (unlikely(ret < 0))
 		goto fill_err;
-- 
2.7.4