### [CVE-2021-47400](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-47400)
![](https://img.shields.io/static/v1?label=Product&message=Linux&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=&color=brightgreen)
![](https://img.shields.io/static/v1?label=Version&message=5.0%20&color=brightgreen)
![](https://img.shields.io/static/v1?label=Version&message=e888402789b9db5de4fcda361331d66dbf0cd9fd%20&color=brightgreen)
![](https://img.shields.io/static/v1?label=Vulnerability&message=n%2Fa&color=blue)

### Description

In the Linux kernel, the following vulnerability has been resolved:net: hns3: do not allow call hns3_nic_net_open repeatedlyhns3_nic_net_open() is not allowed to called repeatly, but thereis no checking for this. When doing device reset and setup tcconcurrently, there is a small oppotunity to call hns3_nic_net_openrepeatedly, and cause kernel bug by calling napi_enable twice.The calltrace information is like below:[ 3078.222780] ------------[ cut here ]------------[ 3078.230255] kernel BUG at net/core/dev.c:6991![ 3078.236224] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP[ 3078.243431] Modules linked in: hns3 hclgevf hclge hnae3 vfio_iommu_type1 vfio_pci vfio_virqfd vfio pv680_mii(O)[ 3078.258880] CPU: 0 PID: 295 Comm: kworker/u8:5 Tainted: G           O      5.14.0-rc4+ #1[ 3078.269102] Hardware name:  , BIOS KpxxxFPGA 1P B600 V181 08/12/2021[ 3078.276801] Workqueue: hclge hclge_service_task [hclge][ 3078.288774] pstate: 60400009 (nZCv daif +PAN -UAO -TCO BTYPE=--)[ 3078.296168] pc : napi_enable+0x80/0x84tc qdisc sho[w  3d0e7v8 .e3t0h218 79] lr : hns3_nic_net_open+0x138/0x510 [hns3][ 3078.314771] sp : ffff8000108abb20[ 3078.319099] x29: ffff8000108abb20 x28: 0000000000000000 x27: ffff0820a8490300[ 3078.329121] x26: 0000000000000001 x25: ffff08209cfc6200 x24: 0000000000000000[ 3078.339044] x23: ffff0820a8490300 x22: ffff08209cd76000 x21: ffff0820abfe3880[ 3078.349018] x20: 0000000000000000 x19: ffff08209cd76900 x18: 0000000000000000[ 3078.358620] x17: 0000000000000000 x16: ffffc816e1727a50 x15: 0000ffff8f4ff930[ 3078.368895] x14: 0000000000000000 x13: 0000000000000000 x12: 0000259e9dbeb6b4[ 3078.377987] x11: 0096a8f7e764eb40 x10: 634615ad28d3eab5 x9 : ffffc816ad8885b8[ 3078.387091] x8 : ffff08209cfc6fb8 x7 : ffff0820ac0da058 x6 : ffff0820a8490344[ 3078.396356] x5 : 0000000000000140 x4 : 0000000000000003 x3 : ffff08209cd76938[ 3078.405365] x2 : 0000000000000000 x1 : 0000000000000010 x0 : ffff0820abfe38a0[ 3078.414657] Call trace:[ 3078.418517]  napi_enable+0x80/0x84[ 3078.424626]  hns3_reset_notify_up_enet+0x78/0xd0 [hns3][ 3078.433469]  hns3_reset_notify+0x64/0x80 [hns3][ 3078.441430]  hclge_notify_client+0x68/0xb0 [hclge][ 3078.450511]  hclge_reset_rebuild+0x524/0x884 [hclge][ 3078.458879]  hclge_reset_service_task+0x3c4/0x680 [hclge][ 3078.467470]  hclge_service_task+0xb0/0xb54 [hclge][ 3078.475675]  process_one_work+0x1dc/0x48c[ 3078.481888]  worker_thread+0x15c/0x464[ 3078.487104]  kthread+0x160/0x170[ 3078.492479]  ret_from_fork+0x10/0x18[ 3078.498785] Code: c8027c81 35ffffa2 d50323bf d65f03c0 (d4210000)[ 3078.506889] ---[ end trace 8ebe0340a1b0fb44 ]---Once hns3_nic_net_open() is excute success, the flagHNS3_NIC_STATE_DOWN will be cleared. So add checking for thisflag, directly return when HNS3_NIC_STATE_DOWN is no set.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/ARPSyndicate/cve-scores