# CVE-2021-47283: net:sfc: fix non-freed irq in legacy irq mode

> A resource leak in the SFC network driver when using legacy IRQ mode can lead to memory exhaustion and denial of service upon module removal.

- **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:** Yes
- **Published:** 21 May 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47283, GHSA-2277-9x7j-58f3, UBUNTU-CVE-2021-47283

## What is CVE-2021-47283?

CVE-2021-47283 is a medium-severity denial of service 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:

net:sfc: fix non-freed irq in legacy irq mode

SFC driver can be configured via modparam to work using MSI-X, MSI or
legacy IRQ interrupts. In the last one, the interrupt was not properly
released on module remove.

It was not freed because the flag irqs_hooked was not set during
initialization in the case of using legacy IRQ.

Example of (trimmed) trace during module remove without this fix:

remove_proc_entry: removing non-empty directory 'irq/125', leaking at least '0000:3b:00.1'
WARNING: CPU: 39 PID: 3658 at fs/proc/generic.c:715 remove_proc_entry+0x15c/0x170
...trimmed...
Call Trace:
 unregister_irq_proc+0xe3/0x100
 free_desc+0x29/0x70
 irq_free_descs+0x47/0x70
 mp_unmap_irq+0x58/0x60
 acpi_unregister_gsi_ioapic+0x2a/0x40
 acpi_pci_irq_disable+0x78/0xb0
 pci_disable_device+0xd1/0x100
 efx_pci_remove+0xa1/0x1e0 [sfc]
 pci_device_remove+0x38/0xa0
 __device_release_driver+0x177/0x230
 driver_detach+0xcb/0x110
 bus_remove_driver+0x58/0xd0
 pci_unregister_driver+0x2a/0xb0
 efx_exit_module+0x24/0xf40 [sfc]
 __do_sys_delete_module.constprop.0+0x171/0x280
 ? exit_to_user_mode_prepare+0x83/0x1d0
 do_syscall_64+0x3d/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f9f9385800b
...trimmed...

Weakness: CWE-772 (Missing Release of Resource after Effective Lifetime)

## Which versions are affected by CVE-2021-47283?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47283?

Apply the vendor's patch.

## Is CVE-2021-47283 being exploited?

There is no known exploitation of CVE-2021-47283 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-2021-47283 and fix it if it is affected.

What it is: CVE-2021-47283 is a medium-severity denial of service 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-2021-47283 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-2021-47283/ (Markdown: https://insights.sbomify.com/CVE-2021-47283/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47283
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47283
- OSV: https://osv.dev/vulnerability/CVE-2021-47283

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47283/
Summaries are generated and may contain mistakes; the official description above is the record.