# CVE-2026-90108: net/smc: free stashed qentry before overwrite in REQ_ADD_LINK to ADD_LINK transition

> A memory leak in the Linux kernel SMC protocol allows remote attackers to exhaust kernel memory, causing denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102848, BELL-CVE-2026-90108, DEBIAN-CVE-2026-90108, GHSA-6x7f-mrc2-297f, UBUNTU-CVE-2026-90108

## What is CVE-2026-90108?

CVE-2026-90108 is a memory corruption vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

net/smc: free stashed qentry before overwrite in REQ_ADD_LINK to ADD_LINK transition

When smc_llc_event_handler() transitions the local LLC flow from
SMC_LLC_FLOW_REQ_ADD_LINK to SMC_LLC_FLOW_ADD_LINK on arrival of an ADD_LINK
request, it calls smc_llc_flow_qentry_set() unconditionally:

	if (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_REQ_ADD_LINK) {
		lgr->llc_flow_lcl.type = SMC_LLC_FLOW_ADD_LINK;
		smc_llc_flow_qentry_set(&lgr->llc_flow_lcl, qentry);
		...
	}

A CONFIRM_LINK or ADD_LINK_CONT arriving while flow->type is
SMC_LLC_FLOW_REQ_ADD_LINK is stashed into flow->qentry via the
SMC_LLC_CONFIRM_LINK / SMC_LLC_ADD_LINK_CONT handler (which stores into
flow->qentry for any non-NONE flow type).  When the subsequent ADD_LINK
arrives, the REQ_ADD_LINK branch overwrites flow->qentry with the new pointer
without first freeing the stashed allocation, leaking one kmalloc object.

The stashed entry has no consumer: smc_llc_wait() is only called from
llc_add_link_work, which is not yet scheduled while the flow type remains
REQ_ADD_LINK.  No waiter is sleeping on llc_msg_waiter at this point.
It is safe to unconditionally free any stashed qentry before
the overwrite.

Call smc_llc_flow_qentry_del() before smc_llc_flow_qentry_set() in the
REQ_ADD_LINK branch.  smc_llc_flow_qentry_del() already checks flow->qentry
before freeing, so the normal path where no entry is stashed is a no-op.

## Which versions are affected by CVE-2026-90108?


## How do I fix CVE-2026-90108?

Apply the vendor's patch.

## Is CVE-2026-90108 being exploited?

There is no known exploitation of CVE-2026-90108 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90108 and fix it if it is affected.

What it is: CVE-2026-90108 is a memory corruption vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90108 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-2026-90108/ (Markdown: https://insights.sbomify.com/CVE-2026-90108/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90108
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90108
- OSV: https://osv.dev/vulnerability/CVE-2026-90108

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90108/
Summaries are generated and may contain mistakes; the official description above is the record.