# CVE-2024-35977: platform/chrome: cros_ec_uart: properly fix race condition

> A race condition in the Linux kernel's Chrome OS EC UART driver can cause a NULL pointer dereference, leading to a system crash.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/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:** 20 May 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2024-35977, DEBIAN-CVE-2024-35977, GHSA-r3pw-96wv-8pj5, UBUNTU-CVE-2024-35977

## What is CVE-2024-35977?

CVE-2024-35977 is a medium-severity vulnerability in Linux kernel, published on 20 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:

platform/chrome: cros_ec_uart: properly fix race condition

The cros_ec_uart_probe() function calls devm_serdev_device_open() before
it calls serdev_device_set_client_ops(). This can trigger a NULL pointer
dereference:

    BUG: kernel NULL pointer dereference, address: 0000000000000000
    ...
    Call Trace:
     <TASK>
     ...
     ? ttyport_receive_buf

A simplified version of crashing code is as follows:

    static inline size_t serdev_controller_receive_buf(struct serdev_controller *ctrl,
                                                      const u8 *data,
                                                      size_t count)
    {
            struct serdev_device *serdev = ctrl->serdev;

            if (!serdev || !serdev->ops->receive_buf) // CRASH!
                return 0;

            return serdev->ops->receive_buf(serdev, data, count);
    }

It assumes that if SERPORT_ACTIVE is set and serdev exists, serdev->ops
will also exist. This conflicts with the existing cros_ec_uart_probe()
logic, as it first calls devm_serdev_device_open() (which sets
SERPORT_ACTIVE), and only later sets serdev->ops via
serdev_device_set_client_ops().

Commit 01f95d42b8f4 ("platform/chrome: cros_ec_uart: fix race
condition") attempted to fix a similar race condition, but while doing
so, made the window of error for this race condition to happen much
wider.

Attempt to fix the race condition again, making sure we fully setup
before calling devm_serdev_device_open().

Weakness: CWE-476 (NULL Pointer Dereference), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2024-35977?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-35977?

Apply the vendor's patch.

## Is CVE-2024-35977 being exploited?

There is no known exploitation of CVE-2024-35977 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-2024-35977 and fix it if it is affected.

What it is: CVE-2024-35977 is a medium-severity vulnerability in Linux kernel, published on 20 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-2024-35977 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-2024-35977/ (Markdown: https://insights.sbomify.com/CVE-2024-35977/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-35977
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-35977
- OSV: https://osv.dev/vulnerability/CVE-2024-35977

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-35977/
Summaries are generated and may contain mistakes; the official description above is the record.