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net: hns3: fix a use after free problem in hns3_nic_maybe_stop_tx()
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Currently, hns3_nic_maybe_stop_tx() uses skb_copy() to linearize a
SKB if the BD num required by the SKB does not meet the hardware
limitation, and it linearizes the SKB by allocating a new linearized SKB
and freeing the old SKB, if hns3_nic_maybe_stop_tx() returns -EBUSY
because there are no enough space in the ring to send the linearized
skb to hardware, the sch_direct_xmit() still hold reference to old SKB
and try to retransmit the old SKB when dev_hard_start_xmit() return
TX_BUSY, which may cause use after freed problem.

This patch fixes it by using __skb_linearize() to linearize the
SKB in hns3_nic_maybe_stop_tx().

Fixes: 51e8439 ("net: hns3: add 8 BD limit for tx flow")
Signed-off-by: Yunsheng Lin <[email protected]>
Signed-off-by: Huazhong Tan <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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Yunsheng Lin authored and davem330 committed Dec 5, 2019
1 parent 2a597ef commit d1a37de
Showing 1 changed file with 6 additions and 13 deletions.
19 changes: 6 additions & 13 deletions drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
Original file line number Diff line number Diff line change
Expand Up @@ -1288,31 +1288,24 @@ static bool hns3_skb_need_linearized(struct sk_buff *skb, unsigned int *bd_size,

static int hns3_nic_maybe_stop_tx(struct hns3_enet_ring *ring,
struct net_device *netdev,
struct sk_buff **out_skb)
struct sk_buff *skb)
{
struct hns3_nic_priv *priv = netdev_priv(netdev);
unsigned int bd_size[HNS3_MAX_TSO_BD_NUM + 1U];
struct sk_buff *skb = *out_skb;
unsigned int bd_num;

bd_num = hns3_tx_bd_num(skb, bd_size);
if (unlikely(bd_num > HNS3_MAX_NON_TSO_BD_NUM)) {
struct sk_buff *new_skb;

if (bd_num <= HNS3_MAX_TSO_BD_NUM && skb_is_gso(skb) &&
!hns3_skb_need_linearized(skb, bd_size, bd_num))
goto out;

/* manual split the send packet */
new_skb = skb_copy(skb, GFP_ATOMIC);
if (!new_skb)
if (__skb_linearize(skb))
return -ENOMEM;
dev_kfree_skb_any(skb);
*out_skb = new_skb;

bd_num = hns3_tx_bd_count(new_skb->len);
if ((skb_is_gso(new_skb) && bd_num > HNS3_MAX_TSO_BD_NUM) ||
(!skb_is_gso(new_skb) &&
bd_num = hns3_tx_bd_count(skb->len);
if ((skb_is_gso(skb) && bd_num > HNS3_MAX_TSO_BD_NUM) ||
(!skb_is_gso(skb) &&
bd_num > HNS3_MAX_NON_TSO_BD_NUM))
return -ENOMEM;

Expand Down Expand Up @@ -1415,7 +1408,7 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
/* Prefetch the data used later */
prefetch(skb->data);

ret = hns3_nic_maybe_stop_tx(ring, netdev, &skb);
ret = hns3_nic_maybe_stop_tx(ring, netdev, skb);
if (unlikely(ret <= 0)) {
if (ret == -EBUSY) {
u64_stats_update_begin(&ring->syncp);
Expand Down

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