# CVE-2026-45984: gfs2: Fix use-after-free in iomap inline data write path

> A use-after-free in the Linux kernel GFS2 filesystem allows attackers to execute arbitrary code or escalate privileges via inline data writes.

- **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:** 27 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-45984, DEBIAN-CVE-2026-45984, GHSA-c7gf-37rm-rpg6, ROOT-OS-DEBIAN-11-CVE-2026-45984, ROOT-OS-UBUNTU-2204-CVE-2026-45984, ROOT-OS-UBUNTU-2404-CVE-2026-45984, UBUNTU-CVE-2026-45984

## What is CVE-2026-45984?

CVE-2026-45984 is a high-severity use after free vulnerability in Linux kernel, published on 27 May 2026. 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:

gfs2: Fix use-after-free in iomap inline data write path

The inline data buffer head (dibh) is being released prematurely in
gfs2_iomap_begin() via release_metapath() while iomap->inline_data
still points to dibh->b_data. This causes a use-after-free when
iomap_write_end_inline() later attempts to write to the inline data
area.

The bug sequence:
1. gfs2_iomap_begin() calls gfs2_meta_inode_buffer() to read inode
   metadata into dibh
2. Sets iomap->inline_data = dibh->b_data + sizeof(struct gfs2_dinode)
3. Calls release_metapath() which calls brelse(dibh), dropping refcount
   to 0
4. kswapd reclaims the page (~39ms later in the syzbot report)
5. iomap_write_end_inline() tries to memcpy() to iomap->inline_data
6. KASAN detects use-after-free write to freed memory

Fix by storing dibh in iomap->private and incrementing its refcount
with get_bh() in gfs2_iomap_begin(). The buffer is then properly
released in gfs2_iomap_end() after the inline write completes,
ensuring the page stays alive for the entire iomap operation.

Note: A C reproducer is not available for this issue. The fix is based
on analysis of the KASAN report and code review showing the buffer head
is freed before use.

[agruenba: Take buffer head reference in gfs2_iomap_begin() to avoid
leaks in gfs2_iomap_get() and gfs2_iomap_alloc().]

Weakness: CWE-416 (Use After Free), CWE-826 (Premature Release of Resource During Expected Lifetime)

## Which versions are affected by CVE-2026-45984?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-45984?

Apply the vendor's patch.

## Is CVE-2026-45984 being exploited?

There is no known exploitation of CVE-2026-45984 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-2026-45984 and fix it if it is affected.

What it is: CVE-2026-45984 is a high-severity use after free vulnerability in Linux kernel, published on 27 May 2026. 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-2026-45984 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-2026-45984/ (Markdown: https://insights.sbomify.com/CVE-2026-45984/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45984
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45984
- OSV: https://osv.dev/vulnerability/CVE-2026-45984

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45984/
Summaries are generated and may contain mistakes; the official description above is the record.