# CVE-2021-47272: usb: dwc3: gadget: Bail from dwc3_gadget_exit() if dwc->gadget is NULL

> A null pointer dereference in the Linux kernel DWC3 USB gadget driver can cause a system crash during specific USB mode switching scenarios.

- **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:** 21 May 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47272, GHSA-jpfh-4v99-5m27, UBUNTU-CVE-2021-47272

## What is CVE-2021-47272?

CVE-2021-47272 is a medium-severity vulnerability in Linux kernel, published on 21 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:

usb: dwc3: gadget: Bail from dwc3_gadget_exit() if dwc->gadget is NULL

There exists a possible scenario in which dwc3_gadget_init() can fail:
during during host -> peripheral mode switch in dwc3_set_mode(), and
a pending gadget driver fails to bind.  Then, if the DRD undergoes
another mode switch from peripheral->host the resulting
dwc3_gadget_exit() will attempt to reference an invalid and dangling
dwc->gadget pointer as well as call dma_free_coherent() on unmapped
DMA pointers.

The exact scenario can be reproduced as follows:
 - Start DWC3 in peripheral mode
 - Configure ConfigFS gadget with FunctionFS instance (or use g_ffs)
 - Run FunctionFS userspace application (open EPs, write descriptors, etc)
 - Bind gadget driver to DWC3's UDC
 - Switch DWC3 to host mode
   => dwc3_gadget_exit() is called. usb_del_gadget() will put the
	ConfigFS driver instance on the gadget_driver_pending_list
 - Stop FunctionFS application (closes the ep files)
 - Switch DWC3 to peripheral mode
   => dwc3_gadget_init() fails as usb_add_gadget() calls
	check_pending_gadget_drivers() and attempts to rebind the UDC
	to the ConfigFS gadget but fails with -19 (-ENODEV) because the
	FFS instance is not in FFS_ACTIVE state (userspace has not
	re-opened and written the descriptors yet, i.e. desc_ready!=0).
 - Switch DWC3 back to host mode
   => dwc3_gadget_exit() is called again, but this time dwc->gadget
	is invalid.

Although it can be argued that userspace should take responsibility
for ensuring that the FunctionFS application be ready prior to
allowing the composite driver bind to the UDC, failure to do so
should not result in a panic from the kernel driver.

Fix this by setting dwc->gadget to NULL in the failure path of
dwc3_gadget_init() and add a check to dwc3_gadget_exit() to bail out
unless the gadget pointer is valid.

## Which versions are affected by CVE-2021-47272?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47272?

Apply the vendor's patch.

## Is CVE-2021-47272 being exploited?

There is no known exploitation of CVE-2021-47272 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-2021-47272 and fix it if it is affected.

What it is: CVE-2021-47272 is a medium-severity vulnerability in Linux kernel, published on 21 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-2021-47272 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-2021-47272/ (Markdown: https://insights.sbomify.com/CVE-2021-47272/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47272
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47272
- OSV: https://osv.dev/vulnerability/CVE-2021-47272

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47272/
Summaries are generated and may contain mistakes; the official description above is the record.