# CVE-2023-53094: tty: serial: fsl_lpuart: fix race on RX DMA shutdown

> A race condition in the Linux kernel's fsl_lpuart serial driver can cause a null pointer dereference and system crash during DMA shutdown.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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:** 2 May 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-53094, DEBIAN-CVE-2023-53094, GHSA-25vh-j698-43q9, UBUNTU-CVE-2023-53094

## What is CVE-2023-53094?

CVE-2023-53094 is a high-severity vulnerability in Linux kernel, published on 2 May 2025. 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: fsl_lpuart: fix race on RX DMA shutdown

From time to time DMA completion can come in the middle of DMA shutdown:

<process ctx>:				<IRQ>:
lpuart32_shutdown()
  lpuart_dma_shutdown()
    del_timer_sync()
					lpuart_dma_rx_complete()
					  lpuart_copy_rx_to_tty()
					    mod_timer()
    lpuart_dma_rx_free()

When the timer fires a bit later, sport->dma_rx_desc is NULL:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004
pc : lpuart_copy_rx_to_tty+0xcc/0x5bc
lr : lpuart_timer_func+0x1c/0x2c
Call trace:
 lpuart_copy_rx_to_tty
 lpuart_timer_func
 call_timer_fn
 __run_timers.part.0
 run_timer_softirq
 __do_softirq
 __irq_exit_rcu
 irq_exit
 handle_domain_irq
 gic_handle_irq
 call_on_irq_stack
 do_interrupt_handler
 ...

To fix this fold del_timer_sync() into lpuart_dma_rx_free() after
dmaengine_terminate_sync() to make sure timer will not be re-started in
lpuart_copy_rx_to_tty() <= lpuart_dma_rx_complete().

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2023-53094?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53094?

Apply the vendor's patch.

## Is CVE-2023-53094 being exploited?

There is no known exploitation of CVE-2023-53094 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-2023-53094 and fix it if it is affected.

What it is: CVE-2023-53094 is a high-severity vulnerability in Linux kernel, published on 2 May 2025. 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-2023-53094 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-2023-53094/ (Markdown: https://insights.sbomify.com/CVE-2023-53094/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53094
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53094
- OSV: https://osv.dev/vulnerability/CVE-2023-53094

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53094/
Summaries are generated and may contain mistakes; the official description above is the record.