# CVE-2026-64528: tty: serial: samsung: Remove redundant port lock acquisition in rx helpers

> A deadlock in the Samsung serial driver causes a denial of service when console flow control is enabled, requiring a kernel patch.

- **Severity:** Not scored
- **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:** 25 Jul 2026
- **Updated:** 25 Jul 2026
- **Also known as:** BELL-CVE-2026-64528, DEBIAN-CVE-2026-64528, GHSA-9gfg-cjvv-9789, ROOT-OS-UBUNTU-2204-CVE-2026-64528, UBUNTU-CVE-2026-64528

## What is CVE-2026-64528?

CVE-2026-64528 is a vulnerability in Linux, published on 25 Jul 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:

tty: serial: samsung: Remove redundant port lock acquisition in rx helpers

Sashiko identified a deadlock when the console flow is engaged [1].

When console flow control is enabled (UPF_CONS_FLOW),
s3c24xx_serial_stop_tx() calls s3c24xx_serial_rx_enable() and
s3c24xx_serial_start_tx() calls s3c24xx_serial_rx_disable().

The serial core framework invokes the .stop_tx() and .start_tx()
callbacks with the port->lock spinlock already held. Furthermore, all
internal driver paths that invoke stop_tx (such as the DMA TX
completion handler s3c24xx_serial_tx_dma_complete() or the PIO TX IRQ
handler s3c24xx_serial_tx_irq()) also acquire port->lock prior to
calling it. (Note that s3c24xx_serial_start_tx() is only invoked by the
serial core).

However, s3c24xx_serial_rx_enable() and s3c24xx_serial_rx_disable()
unconditionally attempt to acquire port->lock again using
uart_port_lock_irqsave(). Since spinlocks are not recursive, this
causes a deadlock on the same CPU when console flow control is engaged.

Remove the redundant lock acquisition from both rx helper functions.

## Which versions are affected by CVE-2026-64528?


## How do I fix CVE-2026-64528?

Apply the vendor's patch.

## Is CVE-2026-64528 being exploited?

There is no known exploitation of CVE-2026-64528 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64528 and fix it if it is affected.

What it is: CVE-2026-64528 is a vulnerability in Linux, published on 25 Jul 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-2026-64528 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-2026-64528/ (Markdown: https://insights.sbomify.com/CVE-2026-64528/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64528
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64528
- OSV: https://osv.dev/vulnerability/CVE-2026-64528

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64528/
Summaries are generated and may contain mistakes; the official description above is the record.