# CVE-2025-39910: mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc()

> A bug in the Linux kernel's KASAN vmalloc handling ignores memory allocation flags, potentially causing deadlocks during XFS operations.

- **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:** 1 Oct 2025
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2025-39910, DEBIAN-CVE-2025-39910, GHSA-xqc4-9x8w-pf49, ROOT-OS-DEBIAN-12-CVE-2025-39910, ROOT-OS-DEBIAN-13-CVE-2025-39910, ROOT-OS-UBUNTU-2404-CVE-2025-39910, UBUNTU-CVE-2025-39910

## What is CVE-2025-39910?

CVE-2025-39910 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Oct 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:

mm/vmalloc, mm/kasan: respect gfp mask in kasan_populate_vmalloc()

kasan_populate_vmalloc() and its helpers ignore the caller's gfp_mask and
always allocate memory using the hardcoded GFP_KERNEL flag.  This makes
them inconsistent with vmalloc(), which was recently extended to support
GFP_NOFS and GFP_NOIO allocations.

Page table allocations performed during shadow population also ignore the
external gfp_mask.  To preserve the intended semantics of GFP_NOFS and
GFP_NOIO, wrap the apply_to_page_range() calls into the appropriate
memalloc scope.

xfs calls vmalloc with GFP_NOFS, so this bug could lead to deadlock.

There was a report here
https://lkml.kernel.org/r/686ea951.050a0220.385921.0016.GAE@google.com

This patch:
 - Extends kasan_populate_vmalloc() and helpers to take gfp_mask;
 - Passes gfp_mask down to alloc_pages_bulk() and __get_free_page();
 - Enforces GFP_NOFS/NOIO semantics with memalloc_*_save()/restore()
   around apply_to_page_range();
 - Updates vmalloc.c and percpu allocator call sites accordingly.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2025-39910?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-39910?

Apply the vendor's patch.

## Is CVE-2025-39910 being exploited?

There is no known exploitation of CVE-2025-39910 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-2025-39910 and fix it if it is affected.

What it is: CVE-2025-39910 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Oct 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-2025-39910 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-2025-39910/ (Markdown: https://insights.sbomify.com/CVE-2025-39910/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39910
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39910
- OSV: https://osv.dev/vulnerability/CVE-2025-39910

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-39910/
Summaries are generated and may contain mistakes; the official description above is the record.