# CVE-2024-35852: mlxsw: spectrum_acl_tcam: Fix memory leak when canceling rehash work

> A memory leak in the Linux kernel mlxsw driver allows attackers to cause denial of service by exhausting system memory through repeated ACL region dismantling.

- **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:** 17 May 2024
- **Updated:** 11 May 2026
- **Also known as:** AZL-42139, BELL-CVE-2024-35852, DEBIAN-CVE-2024-35852, GHSA-r32h-q4vw-rvf3, UBUNTU-CVE-2024-35852

## What is CVE-2024-35852?

CVE-2024-35852 is a medium-severity memory corruption vulnerability in Linux kernel, published on 17 May 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:

mlxsw: spectrum_acl_tcam: Fix memory leak when canceling rehash work

The rehash delayed work is rescheduled with a delay if the number of
credits at end of the work is not negative as supposedly it means that
the migration ended. Otherwise, it is rescheduled immediately.

After "mlxsw: spectrum_acl_tcam: Fix possible use-after-free during
rehash" the above is no longer accurate as a non-negative number of
credits is no longer indicative of the migration being done. It can also
happen if the work encountered an error in which case the migration will
resume the next time the work is scheduled.

The significance of the above is that it is possible for the work to be
pending and associated with hints that were allocated when the migration
started. This leads to the hints being leaked [1] when the work is
canceled while pending as part of ACL region dismantle.

Fix by freeing the hints if hints are associated with a work that was
canceled while pending.

Blame the original commit since the reliance on not having a pending
work associated with hints is fragile.

[1]
unreferenced object 0xffff88810e7c3000 (size 256):
  comm "kworker/0:16", pid 176, jiffies 4295460353
  hex dump (first 32 bytes):
    00 30 95 11 81 88 ff ff 61 00 00 00 00 00 00 80  .0......a.......
    00 00 61 00 40 00 00 00 00 00 00 00 04 00 00 00  ..a.@...........
  backtrace (crc 2544ddb9):
    [<00000000cf8cfab3>] kmalloc_trace+0x23f/0x2a0
    [<000000004d9a1ad9>] objagg_hints_get+0x42/0x390
    [<000000000b143cf3>] mlxsw_sp_acl_erp_rehash_hints_get+0xca/0x400
    [<0000000059bdb60a>] mlxsw_sp_acl_tcam_vregion_rehash_work+0x868/0x1160
    [<00000000e81fd734>] process_one_work+0x59c/0xf20
    [<00000000ceee9e81>] worker_thread+0x799/0x12c0
    [<00000000bda6fe39>] kthread+0x246/0x300
    [<0000000070056d23>] ret_from_fork+0x34/0x70
    [<00000000dea2b93e>] ret_from_fork_asm+0x1a/0x30

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2024-35852?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-35852?

Apply the vendor's patch.

## Is CVE-2024-35852 being exploited?

There is no known exploitation of CVE-2024-35852 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-2024-35852 and fix it if it is affected.

What it is: CVE-2024-35852 is a medium-severity memory corruption vulnerability in Linux kernel, published on 17 May 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-2024-35852 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-2024-35852/ (Markdown: https://insights.sbomify.com/CVE-2024-35852/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-35852
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-35852
- OSV: https://osv.dev/vulnerability/CVE-2024-35852

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-35852/
Summaries are generated and may contain mistakes; the official description above is the record.
