# CVE-2022-48897: arm64/mm: fix incorrect file_map_count for invalid pmd

> A bug in the Linux kernel arm64 memory management causes a kernel panic when splitting hugepages, leading to denial of service.

- **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 Aug 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-48897, GHSA-j4gx-6m2g-9p7c, UBUNTU-CVE-2022-48897

## What is CVE-2022-48897?

CVE-2022-48897 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 Aug 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:

arm64/mm: fix incorrect file_map_count for invalid pmd

The page table check trigger BUG_ON() unexpectedly when split hugepage:

 ------------[ cut here ]------------
 kernel BUG at mm/page_table_check.c:119!
 Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
 Dumping ftrace buffer:
    (ftrace buffer empty)
 Modules linked in:
 CPU: 7 PID: 210 Comm: transhuge-stres Not tainted 6.1.0-rc3+ #748
 Hardware name: linux,dummy-virt (DT)
 pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : page_table_check_set.isra.0+0x398/0x468
 lr : page_table_check_set.isra.0+0x1c0/0x468
[...]
 Call trace:
  page_table_check_set.isra.0+0x398/0x468
  __page_table_check_pte_set+0x160/0x1c0
  __split_huge_pmd_locked+0x900/0x1648
  __split_huge_pmd+0x28c/0x3b8
  unmap_page_range+0x428/0x858
  unmap_single_vma+0xf4/0x1c8
  zap_page_range+0x2b0/0x410
  madvise_vma_behavior+0xc44/0xe78
  do_madvise+0x280/0x698
  __arm64_sys_madvise+0x90/0xe8
  invoke_syscall.constprop.0+0xdc/0x1d8
  do_el0_svc+0xf4/0x3f8
  el0_svc+0x58/0x120
  el0t_64_sync_handler+0xb8/0xc0
  el0t_64_sync+0x19c/0x1a0
[...]

On arm64, pmd_leaf() will return true even if the pmd is invalid due to
pmd_present_invalid() check. So in pmdp_invalidate() the file_map_count
will not only decrease once but also increase once. Then in set_pte_at(),
the file_map_count increase again, and so trigger BUG_ON() unexpectedly.

Add !pmd_present_invalid() check in pmd_user_accessible_page() to fix the
problem.

## Which versions are affected by CVE-2022-48897?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-48897?

Apply the vendor's patch.

## Is CVE-2022-48897 being exploited?

There is no known exploitation of CVE-2022-48897 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-2022-48897 and fix it if it is affected.

What it is: CVE-2022-48897 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 Aug 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-2022-48897 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-2022-48897/ (Markdown: https://insights.sbomify.com/CVE-2022-48897/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-48897
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-48897
- OSV: https://osv.dev/vulnerability/CVE-2022-48897

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-48897/
Summaries are generated and may contain mistakes; the official description above is the record.