Code: static netdev_tx_t hns_nic_net_xmit(struct sk_buff *skb,
 				    struct net_device *ndev)
 {
 	struct hns_nic_priv *priv = netdev_priv(ndev);
	int ret;
 
 	assert(skb->queue_mapping < ndev->ae_handle->q_num);
	ret = hns_nic_net_xmit_hw(ndev, skb,
				  &tx_ring_data(priv, skb->queue_mapping));
	if (ret == NETDEV_TX_OK) {
		netif_trans_update(ndev);
		ndev->stats.tx_bytes += skb->len;
		ndev->stats.tx_packets++;
	}
	return (netdev_tx_t)ret;
 }

Vulnerability Type: DoS 
CWE ID: CWE-416
Summary: In drivers/net/ethernet/hisilicon/hns/hns_enet.c in the Linux kernel before 4.13, local users can cause a denial of service (use-after-free and BUG) or possibly have unspecified other impact by leveraging differences in skb handling between hns_nic_net_xmit_hw and hns_nic_net_xmit.
Commit Message: net: hns: Fix a skb used after free bug

skb maybe freed in hns_nic_net_xmit_hw() and return NETDEV_TX_OK,
which cause hns_nic_net_xmit to use a freed skb.

BUG: KASAN: use-after-free in hns_nic_net_xmit_hw+0x62c/0x940...
	[17659.112635]      alloc_debug_processing+0x18c/0x1a0
	[17659.117208]      __slab_alloc+0x52c/0x560
	[17659.120909]      kmem_cache_alloc_node+0xac/0x2c0
	[17659.125309]      __alloc_skb+0x6c/0x260
	[17659.128837]      tcp_send_ack+0x8c/0x280
	[17659.132449]      __tcp_ack_snd_check+0x9c/0xf0
	[17659.136587]      tcp_rcv_established+0x5a4/0xa70
	[17659.140899]      tcp_v4_do_rcv+0x27c/0x620
	[17659.144687]      tcp_prequeue_process+0x108/0x170
	[17659.149085]      tcp_recvmsg+0x940/0x1020
	[17659.152787]      inet_recvmsg+0x124/0x180
	[17659.156488]      sock_recvmsg+0x64/0x80
	[17659.160012]      SyS_recvfrom+0xd8/0x180
	[17659.163626]      __sys_trace_return+0x0/0x4
	[17659.167506] INFO: Freed in kfree_skbmem+0xa0/0xb0 age=23 cpu=1 pid=13
	[17659.174000]      free_debug_processing+0x1d4/0x2c0
	[17659.178486]      __slab_free+0x240/0x390
	[17659.182100]      kmem_cache_free+0x24c/0x270
	[17659.186062]      kfree_skbmem+0xa0/0xb0
	[17659.189587]      __kfree_skb+0x28/0x40
	[17659.193025]      napi_gro_receive+0x168/0x1c0
	[17659.197074]      hns_nic_rx_up_pro+0x58/0x90
	[17659.201038]      hns_nic_rx_poll_one+0x518/0xbc0
	[17659.205352]      hns_nic_common_poll+0x94/0x140
	[17659.209576]      net_rx_action+0x458/0x5e0
	[17659.213363]      __do_softirq+0x1b8/0x480
	[17659.217062]      run_ksoftirqd+0x64/0x80
	[17659.220679]      smpboot_thread_fn+0x224/0x310
	[17659.224821]      kthread+0x150/0x170
	[17659.228084]      ret_from_fork+0x10/0x40

	BUG: KASAN: use-after-free in hns_nic_net_xmit+0x8c/0xc0...
	[17751.080490]      __slab_alloc+0x52c/0x560
	[17751.084188]      kmem_cache_alloc+0x244/0x280
	[17751.088238]      __build_skb+0x40/0x150
	[17751.091764]      build_skb+0x28/0x100
	[17751.095115]      __alloc_rx_skb+0x94/0x150
	[17751.098900]      __napi_alloc_skb+0x34/0x90
	[17751.102776]      hns_nic_rx_poll_one+0x180/0xbc0
	[17751.107097]      hns_nic_common_poll+0x94/0x140
	[17751.111333]      net_rx_action+0x458/0x5e0
	[17751.115123]      __do_softirq+0x1b8/0x480
	[17751.118823]      run_ksoftirqd+0x64/0x80
	[17751.122437]      smpboot_thread_fn+0x224/0x310
	[17751.126575]      kthread+0x150/0x170
	[17751.129838]      ret_from_fork+0x10/0x40
	[17751.133454] INFO: Freed in kfree_skbmem+0xa0/0xb0 age=19 cpu=7 pid=43
	[17751.139951]      free_debug_processing+0x1d4/0x2c0
	[17751.144436]      __slab_free+0x240/0x390
	[17751.148051]      kmem_cache_free+0x24c/0x270
	[17751.152014]      kfree_skbmem+0xa0/0xb0
	[17751.155543]      __kfree_skb+0x28/0x40
	[17751.159022]      napi_gro_receive+0x168/0x1c0
	[17751.163074]      hns_nic_rx_up_pro+0x58/0x90
	[17751.167041]      hns_nic_rx_poll_one+0x518/0xbc0
	[17751.171358]      hns_nic_common_poll+0x94/0x140
	[17751.175585]      net_rx_action+0x458/0x5e0
	[17751.179373]      __do_softirq+0x1b8/0x480
	[17751.183076]      run_ksoftirqd+0x64/0x80
	[17751.186691]      smpboot_thread_fn+0x224/0x310
	[17751.190826]      kthread+0x150/0x170
	[17751.194093]      ret_from_fork+0x10/0x40

Fixes: 13ac695e7ea1 ("net:hns: Add support of Hip06 SoC to the Hislicon Network Subsystem")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: lipeng <lipeng321@huawei.com>
Reported-by: Jun He <hjat2005@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>