# CVE-2021-47271: usb: cdnsp: Fix deadlock issue in cdnsp_thread_irq_handler

> A deadlock in the Linux kernel's cdnsp USB driver can cause a system hang, requiring a patch to resolve.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 May 2024
- **Updated:** 11 May 2026
- **Also known as:** GHSA-7qvv-hm32-963p, UBUNTU-CVE-2021-47271

## What is CVE-2021-47271?

CVE-2021-47271 is a medium-severity vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

usb: cdnsp: Fix deadlock issue in cdnsp_thread_irq_handler

Patch fixes the following critical issue caused by deadlock which has been
detected during testing NCM class:

smp: csd: Detected non-responsive CSD lock (#1) on CPU#0
smp:     csd: CSD lock (#1) unresponsive.
....
RIP: 0010:native_queued_spin_lock_slowpath+0x61/0x1d0
RSP: 0018:ffffbc494011cde0 EFLAGS: 00000002
RAX: 0000000000000101 RBX: ffff9ee8116b4a68 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9ee8116b4658
RBP: ffffbc494011cde0 R08: 0000000000000001 R09: 0000000000000000
R10: ffff9ee8116b4670 R11: 0000000000000000 R12: ffff9ee8116b4658
R13: ffff9ee8116b4670 R14: 0000000000000246 R15: ffff9ee8116b4658
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7bcc41a830 CR3: 000000007a612003 CR4: 00000000001706e0
Call Trace:
 <IRQ>
 do_raw_spin_lock+0xc0/0xd0
 _raw_spin_lock_irqsave+0x95/0xa0
 cdnsp_gadget_ep_queue.cold+0x88/0x107 [cdnsp_udc_pci]
 usb_ep_queue+0x35/0x110
 eth_start_xmit+0x220/0x3d0 [u_ether]
 ncm_tx_timeout+0x34/0x40 [usb_f_ncm]
 ? ncm_free_inst+0x50/0x50 [usb_f_ncm]
 __hrtimer_run_queues+0xac/0x440
 hrtimer_run_softirq+0x8c/0xb0
 __do_softirq+0xcf/0x428
 asm_call_irq_on_stack+0x12/0x20
 </IRQ>
 do_softirq_own_stack+0x61/0x70
 irq_exit_rcu+0xc1/0xd0
 sysvec_apic_timer_interrupt+0x52/0xb0
 asm_sysvec_apic_timer_interrupt+0x12/0x20
RIP: 0010:do_raw_spin_trylock+0x18/0x40
RSP: 0018:ffffbc494138bda8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff9ee8116b4658 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff9ee8116b4658
RBP: ffffbc494138bda8 R08: 0000000000000001 R09: 0000000000000000
R10: ffff9ee8116b4670 R11: 0000000000000000 R12: ffff9ee8116b4658
R13: ffff9ee8116b4670 R14: ffff9ee7b5c73d80 R15: ffff9ee8116b4000
 _raw_spin_lock+0x3d/0x70
 ? cdnsp_thread_irq_handler.cold+0x32/0x112c [cdnsp_udc_pci]
 cdnsp_thread_irq_handler.cold+0x32/0x112c [cdnsp_udc_pci]
 ? cdnsp_remove_request+0x1f0/0x1f0 [cdnsp_udc_pci]
 ? cdnsp_thread_irq_handler+0x5/0xa0 [cdnsp_udc_pci]
 ? irq_thread+0xa0/0x1c0
 irq_thread_fn+0x28/0x60
 irq_thread+0x105/0x1c0
 ? __kthread_parkme+0x42/0x90
 ? irq_forced_thread_fn+0x90/0x90
 ? wake_threads_waitq+0x30/0x30
 ? irq_thread_check_affinity+0xe0/0xe0
 kthread+0x12a/0x160
 ? kthread_park+0x90/0x90
 ret_from_fork+0x22/0x30

The root cause of issue is spin_lock/spin_unlock instruction instead
spin_lock_irqsave/spin_lock_irqrestore in cdnsp_thread_irq_handler
function.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2021-47271?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47271?

No fix has been published for CVE-2021-47271 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-47271 being exploited?

There is no known exploitation of CVE-2021-47271 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-47271 and fix it if it is affected.

What it is: CVE-2021-47271 is a medium-severity vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-47271 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-47271/ (Markdown: https://insights.sbomify.com/CVE-2021-47271/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47271
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47271
- OSV: https://osv.dev/vulnerability/CVE-2021-47271

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47271/
Summaries are generated and may contain mistakes; the official description above is the record.