# CVE-2024-56670: usb: gadget: u_serial: Fix the issue that gs_start_io crashed due to accessing null pointer

> A race condition in the Linux kernel USB gadget driver causes a null pointer dereference and system crash when disconnecting during open operations.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/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:** 27 Dec 2024
- **Updated:** 11 May 2026
- **Also known as:** AZL-54759, AZL-54868, BELL-CVE-2024-56670, DEBIAN-CVE-2024-56670, GHSA-32x8-xhwp-vhg9, UBUNTU-CVE-2024-56670

## What is CVE-2024-56670?

CVE-2024-56670 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 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:

usb: gadget: u_serial: Fix the issue that gs_start_io crashed due to accessing null pointer

Considering that in some extreme cases,
when u_serial driver is accessed by multiple threads,
Thread A is executing the open operation and calling the gs_open,
Thread B is executing the disconnect operation and calling the
gserial_disconnect function,The port->port_usb pointer will be set to NULL.

E.g.
    Thread A                                 Thread B
    gs_open()                                gadget_unbind_driver()
    gs_start_io()                            composite_disconnect()
    gs_start_rx()                            gserial_disconnect()
    ...                                      ...
    spin_unlock(&port->port_lock)
    status = usb_ep_queue()                  spin_lock(&port->port_lock)
    spin_lock(&port->port_lock)              port->port_usb = NULL
    gs_free_requests(port->port_usb->in)     spin_unlock(&port->port_lock)
    Crash

This causes thread A to access a null pointer (port->port_usb is null)
when calling the gs_free_requests function, causing a crash.

If port_usb is NULL, the release request will be skipped as it
will be done by gserial_disconnect.

So add a null pointer check to gs_start_io before attempting
to access the value of the pointer port->port_usb.

Call trace:
 gs_start_io+0x164/0x25c
 gs_open+0x108/0x13c
 tty_open+0x314/0x638
 chrdev_open+0x1b8/0x258
 do_dentry_open+0x2c4/0x700
 vfs_open+0x2c/0x3c
 path_openat+0xa64/0xc60
 do_filp_open+0xb8/0x164
 do_sys_openat2+0x84/0xf0
 __arm64_sys_openat+0x70/0x9c
 invoke_syscall+0x58/0x114
 el0_svc_common+0x80/0xe0
 do_el0_svc+0x1c/0x28
 el0_svc+0x38/0x68

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-56670?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-56670?

Apply the vendor's patch.

## Is CVE-2024-56670 being exploited?

There is no known exploitation of CVE-2024-56670 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-2024-56670 and fix it if it is affected.

What it is: CVE-2024-56670 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 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-2024-56670 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-2024-56670/ (Markdown: https://insights.sbomify.com/CVE-2024-56670/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56670
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56670
- OSV: https://osv.dev/vulnerability/CVE-2024-56670

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56670/
Summaries are generated and may contain mistakes; the official description above is the record.