# CVE-2024-33847: f2fs: compress: don't allow unaligned truncation on released compress inode

> A local attacker can corrupt the f2fs filesystem by performing unaligned truncation on a released compressed inode, leading to data integrity issues and potential denial of service.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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:** 24 Jun 2024
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2024-33847, DEBIAN-CVE-2024-33847, GHSA-8wrm-f3cq-6c93, UBUNTU-CVE-2024-33847

## What is CVE-2024-33847?

CVE-2024-33847 is a high-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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:

f2fs: compress: don't allow unaligned truncation on released compress inode

f2fs image may be corrupted after below testcase:
- mkfs.f2fs -O extra_attr,compression -f /dev/vdb
- mount /dev/vdb /mnt/f2fs
- touch /mnt/f2fs/file
- f2fs_io setflags compression /mnt/f2fs/file
- dd if=/dev/zero of=/mnt/f2fs/file bs=4k count=4
- f2fs_io release_cblocks /mnt/f2fs/file
- truncate -s 8192 /mnt/f2fs/file
- umount /mnt/f2fs
- fsck.f2fs /dev/vdb

[ASSERT] (fsck_chk_inode_blk:1256)  --> ino: 0x5 has i_blocks: 0x00000002, but has 0x3 blocks
[FSCK] valid_block_count matching with CP             [Fail] [0x4, 0x5]
[FSCK] other corrupted bugs                           [Fail]

The reason is: partial truncation assume compressed inode has reserved
blocks, after partial truncation, valid block count may change w/o
.i_blocks and .total_valid_block_count update, result in corruption.

This patch only allow cluster size aligned truncation on released
compress inode for fixing.

## Which versions are affected by CVE-2024-33847?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-33847?

Apply the vendor's patch.

## Is CVE-2024-33847 being exploited?

There is no known exploitation of CVE-2024-33847 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-2024-33847 and fix it if it is affected.

What it is: CVE-2024-33847 is a high-severity denial of service vulnerability in Linux kernel, published on 24 Jun 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-2024-33847 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-2024-33847/ (Markdown: https://insights.sbomify.com/CVE-2024-33847/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-33847
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-33847
- OSV: https://osv.dev/vulnerability/CVE-2024-33847

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-33847/
Summaries are generated and may contain mistakes; the official description above is the record.