# CVE-2026-74734: firewire: ohci: fix NULL pointer dereference in ar_context_release

> A local attacker can cause a kernel crash via a NULL pointer dereference in the FireWire OHCI driver during device probe failure.

- **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:** 26 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-97832, BELL-CVE-2026-74734, DEBIAN-CVE-2026-74734, GHSA-q794-m3rx-76gj, UBUNTU-CVE-2026-74734

## What is CVE-2026-74734?

CVE-2026-74734 is a vulnerability in Linux, published on 26 Aug 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:

firewire: ohci: fix NULL pointer dereference in ar_context_release

During the error handling path of the driver's probe function, a NULL
pointer dereference can occur in ar_context_release().

When pci_probe() fails early (e.g., if pcim_enable_device() or MMIO mapping
fails), the devres cleanup mechanism invokes release_ohci(). This function
unconditionally calls ar_context_release() to clean up the asynchronous
receive contexts. However, if ar_context_init() was not yet called,
ctx->ohci remains NULL (as the fw_ohci structure is zero-initialized by
devres_alloc()).

ar_context_release() immediately dereferences ctx->ohci to get the dev
pointer before checking if the context was actually initialized, leading to
a crash:

Oops: general protection fault, probably for non-canonical address
0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
RIP: 0010:ar_context_release+0x3f/0x380 drivers/firewire/ohci.c:543
Call Trace:
 release_ohci+0x3f/0x60 drivers/firewire/ohci.c:3567
 release_nodes drivers/base/devres.c:546 [inline]
 devres_release_all+0x1a8/0x260 drivers/base/devres.c:576
 device_unbind_cleanup drivers/base/dd.c:597 [inline]
 really_probe+0x451/0xae0 drivers/base/dd.c:772

To fix this, move the assignment of the dev pointer after the !ctx->buffer
check. If ctx->buffer is NULL, it indicates that the context was never
successfully initialized and there is nothing to release, safely avoiding
the dereference of the uninitialized ctx->ohci pointer.

## Which versions are affected by CVE-2026-74734?


## How do I fix CVE-2026-74734?

Apply the vendor's patch.

## Is CVE-2026-74734 being exploited?

There is no known exploitation of CVE-2026-74734 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74734 and fix it if it is affected.

What it is: CVE-2026-74734 is a vulnerability in Linux, published on 26 Aug 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-2026-74734 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-2026-74734/ (Markdown: https://insights.sbomify.com/CVE-2026-74734/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74734
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74734
- OSV: https://osv.dev/vulnerability/CVE-2026-74734

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74734/
Summaries are generated and may contain mistakes; the official description above is the record.