# CVE-2026-74729: soc: aspeed: lpc-snoop: Fix usercopy overflow in snoop_file_read

> A race condition in the Aspeed LPC snoop driver allows local attackers to read kernel memory or crash the system via concurrent FIFO access.

- **Severity:** Not scored
- **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:** 22 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-74729, DEBIAN-CVE-2026-74729, GHSA-6hj9-w6w6-x26p, UBUNTU-CVE-2026-74729

## What is CVE-2026-74729?

CVE-2026-74729 is a vulnerability in Linux, published on 22 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:

soc: aspeed: lpc-snoop: Fix usercopy overflow in snoop_file_read

put_fifo_with_discard() acts as both producer and consumer on the kfifo:
it calls kfifo_skip() (advances out) and kfifo_put() (advances in) from
the IRQ handler without synchronizing with snoop_file_read(), which also
consumes via kfifo_to_user(). On SMP systems this concurrent access can
leave (in - out) larger than the ring buffer, so __kfifo_to_user()'s clamp
to (in - out) is ineffective and kfifo_copy_to_user() can attempt a
copy_to_user() past the kmalloc-2k backing store:

  usercopy: Kernel memory exposure attempt detected from SLUB object
  'kmalloc-2k' (offset 0, size 2049)!
  kernel BUG at mm/usercopy.c!
  Call trace:
   usercopy_abort
   __check_heap_object
   __check_object_size
   kfifo_copy_to_user
   __kfifo_to_user
   snoop_file_read
   vfs_read

Serialize kfifo access with a per-channel spinlock shared between the
IRQ handler (producer) and the file reader (consumer).  Annotate @fifo
with __guarded_by(&lock) and opt the driver into context analysis so the
compiler enforces that all fifo access holds the lock.

## Which versions are affected by CVE-2026-74729?


## How do I fix CVE-2026-74729?

Apply the vendor's patch.

## Is CVE-2026-74729 being exploited?

There is no known exploitation of CVE-2026-74729 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74729 and fix it if it is affected.

What it is: CVE-2026-74729 is a vulnerability in Linux, published on 22 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-2026-74729 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-2026-74729/ (Markdown: https://insights.sbomify.com/CVE-2026-74729/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74729
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74729
- OSV: https://osv.dev/vulnerability/CVE-2026-74729

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74729/
Summaries are generated and may contain mistakes; the official description above is the record.