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Linux KernelOperating system · Linux

CVE-2021-47400

MEDIUM · 5.5 CVSS v3.1 Published 2024-05-21
Fix available
A fix is available. Upgrade to 5.4.151 / 5.10.71 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: net: hns3: do not allow call hns3_nic_net_open repeatedly hns3_nic_net_open() is not allowed to called repeatly, but there is no checking for this. When doing device reset and setup tc concurrently, there is a small oppotunity to call hns3_nic_net_open repeatedly, 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+0x80/0x84 tc 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 flag HNS3_NIC_STATE_DOWN will be cleared. So add checking for this flag, directly return when HNS3_NIC_STATE_DOWN is no set.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.0, < 5.4.151>= 5.5, < 5.10.71>= 5.11, < 5.14.10= 5.15

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.4.151 / 5.10.71 / 5.14.10 or later
Fixed in 5.4.1515.10.715.14.10
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel version 5.4.151, 5.10.71, 5.14.10, or any version after 5.15 (e.g., 5.15.1+) depending on your current branch

  1. Identify the currently running Linux kernel version using 'uname -r'
  2. Based on the kernel version, upgrade to one of the fixed releases: 5.4.151 or later for 5.4.x kernels, 5.10.71 or later for 5.10.x kernels, 5.14.10 or later for 5.14.x kernels, or a version after 5.15 that includes the fix (e.g., 5.15.1 or later)
  3. After upgrading the kernel, reboot the system to load the fixed version
  4. Verify the fix is applied by checking that hns3_nic_net_open now properly checks the HNS3_NIC_STATE_DOWN flag before proceeding
Caveat No breaking changes - this is a bug fix that adds a safety check to prevent double napi_enable calls

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-47400 in production — separate from our analysis above.

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