# CVE-2023-53224: ext4: Fix function prototype mismatch for ext4_feat_ktype

> A kernel panic occurs when unloading the ext4 module due to a function prototype mismatch, requiring a patched kernel to prevent system crashes.

- **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:** 15 Sep 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53224, DEBIAN-CVE-2023-53224, GHSA-9x2c-7hh8-w98c, UBUNTU-CVE-2023-53224

## What is CVE-2023-53224?

CVE-2023-53224 is a medium-severity denial of service vulnerability in Linux kernel, published on 15 Sep 2025. 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:

ext4: Fix function prototype mismatch for ext4_feat_ktype

With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed.

ext4_feat_ktype was setting the "release" handler to "kfree", which
doesn't have a matching function prototype. Add a simple wrapper
with the correct prototype.

This was found as a result of Clang's new -Wcast-function-type-strict
flag, which is more sensitive than the simpler -Wcast-function-type,
which only checks for type width mismatches.

Note that this code is only reached when ext4 is a loadable module and
it is being unloaded:

 CFI failure at kobject_put+0xbb/0x1b0 (target: kfree+0x0/0x180; expected type: 0x7c4aa698)
 ...
 RIP: 0010:kobject_put+0xbb/0x1b0
 ...
 Call Trace:
  <TASK>
  ext4_exit_sysfs+0x14/0x60 [ext4]
  cleanup_module+0x67/0xedb [ext4]

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2023-53224?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53224?

Apply the vendor's patch.

## Is CVE-2023-53224 being exploited?

There is no known exploitation of CVE-2023-53224 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-2023-53224 and fix it if it is affected.

What it is: CVE-2023-53224 is a medium-severity denial of service vulnerability in Linux kernel, published on 15 Sep 2025. 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-2023-53224 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-2023-53224/ (Markdown: https://insights.sbomify.com/CVE-2023-53224/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53224
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53224
- OSV: https://osv.dev/vulnerability/CVE-2023-53224

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53224/
Summaries are generated and may contain mistakes; the official description above is the record.