# CVE-2026-89856: scsi: qla2xxx: Clamp MSI-X derived queue counts to avoid truncation

> A malicious or misconfigured device can trigger integer truncation in the qla2xxx driver, leading to memory corruption or kernel crashes.

- **Severity:** High 8.4 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101363, BELL-CVE-2026-89856, DEBIAN-CVE-2026-89856, GHSA-m9fj-xvr8-vh59, UBUNTU-CVE-2026-89856

## What is CVE-2026-89856?

CVE-2026-89856 is a high-severity vulnerability in Linux, published on 16 Sep 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:

scsi: qla2xxx: Clamp MSI-X derived queue counts to avoid truncation

ha->msix_count is u16, but ha->max_req_queues, ha->max_rsp_queues and
ha->max_qpairs are u8. Deriving the queue count as
"ha->max_req_queues = ha->msix_count - 1" therefore truncates: a board
(or a misconfigured/malicious hot-plugged device) advertising 257 MSI-X
vectors yields msix_count - 1 == 256, which truncates to 0. An MSI-X
count of 1 zeroes it as well, and in target mode the subsequent
"ha->max_req_queues--" then underflows 0 to 255.

When the count is 0, qla2x00_alloc_queues() calls
kzalloc_objs(struct req_que *, 0), which returns ZERO_SIZE_PTR. That is
not NULL, so the allocation check passes and the following
"ha->req_q_map[0] = req" dereferences ZERO_SIZE_PTR, corrupting memory
or crashing the kernel.

Add qla_calc_queue_count() to clamp the derived value into
[1, QLA_MAX_QUEUES - 1] so it always fits in u8 and is never zero, and
use it at all three derivation sites (qla25xx_iospace_config(),
qla83xx_iospace_config() and qla24xx_enable_msix()). Also guard the
target-mode decrement so it cannot reintroduce a zero (which would in
turn underflow max_qpairs).

## Which versions are affected by CVE-2026-89856?


## How do I fix CVE-2026-89856?

Apply the vendor's patch.

## Is CVE-2026-89856 being exploited?

There is no known exploitation of CVE-2026-89856 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89856 and fix it if it is affected.

What it is: CVE-2026-89856 is a high-severity vulnerability in Linux, published on 16 Sep 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-2026-89856 in the wild and no public exploit code.

Affected product: Linux. 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-2026-89856/ (Markdown: https://insights.sbomify.com/CVE-2026-89856/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89856
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89856
- OSV: https://osv.dev/vulnerability/CVE-2026-89856

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89856/
Summaries are generated and may contain mistakes; the official description above is the record.