# CVE-2024-56678: powerpc/mm/fault: Fix kfence page fault reporting

> A local attacker can trigger a kernel crash by reading /proc/kcore, causing a use-after-free error in the KFENCE memory debugging subsystem.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 28 Dec 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2024-56678, DEBIAN-CVE-2024-56678, GHSA-v5r3-wf29-qq37, UBUNTU-CVE-2024-56678

## What is CVE-2024-56678?

CVE-2024-56678 is a high-severity use after free vulnerability in Linux kernel, published on 28 Dec 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:

powerpc/mm/fault: Fix kfence page fault reporting

copy_from_kernel_nofault() can be called when doing read of /proc/kcore.
/proc/kcore can have some unmapped kfence objects which when read via
copy_from_kernel_nofault() can cause page faults. Since *_nofault()
functions define their own fixup table for handling fault, use that
instead of asking kfence to handle such faults.

Hence we search the exception tables for the nip which generated the
fault. If there is an entry then we let the fixup table handler handle the
page fault by returning an error from within ___do_page_fault().

This can be easily triggered if someone tries to do dd from /proc/kcore.
eg. dd if=/proc/kcore of=/dev/null bs=1M

Some example false negatives:

  ===============================
  BUG: KFENCE: invalid read in copy_from_kernel_nofault+0x9c/0x1a0
  Invalid read at 0xc0000000fdff0000:
   copy_from_kernel_nofault+0x9c/0x1a0
   0xc00000000665f950
   read_kcore_iter+0x57c/0xa04
   proc_reg_read_iter+0xe4/0x16c
   vfs_read+0x320/0x3ec
   ksys_read+0x90/0x154
   system_call_exception+0x120/0x310
   system_call_vectored_common+0x15c/0x2ec

  BUG: KFENCE: use-after-free read in copy_from_kernel_nofault+0x9c/0x1a0
  Use-after-free read at 0xc0000000fe050000 (in kfence-#2):
   copy_from_kernel_nofault+0x9c/0x1a0
   0xc00000000665f950
   read_kcore_iter+0x57c/0xa04
   proc_reg_read_iter+0xe4/0x16c
   vfs_read+0x320/0x3ec
   ksys_read+0x90/0x154
   system_call_exception+0x120/0x310
   system_call_vectored_common+0x15c/0x2ec

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-56678?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-56678?

Apply the vendor's patch.

## Is CVE-2024-56678 being exploited?

There is no known exploitation of CVE-2024-56678 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-2024-56678 and fix it if it is affected.

What it is: CVE-2024-56678 is a high-severity use after free vulnerability in Linux kernel, published on 28 Dec 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-2024-56678 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-2024-56678/ (Markdown: https://insights.sbomify.com/CVE-2024-56678/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56678
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56678
- OSV: https://osv.dev/vulnerability/CVE-2024-56678

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56678/
Summaries are generated and may contain mistakes; the official description above is the record.