# CVE-2026-90012: spi: Fix DMA mapping ownership on partial map failure

> A null pointer dereference in the Linux kernel SPI driver can cause a system crash when DMA mapping fails partially.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-90012, DEBIAN-CVE-2026-90012, GHSA-xm4q-v74w-px7x, UBUNTU-CVE-2026-90012

## What is CVE-2026-90012?

CVE-2026-90012 is a critical vulnerability in Linux, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

spi: Fix DMA mapping ownership on partial map failure

If RX mapping fails after TX mapping succeeds, __spi_map_msg() unmaps
TX but leaves tx_sg_mapped set. If TX mapping fails on a later
transfer, mappings created for earlier transfers remain active.

In both cases, cur_{tx,rx}_dma_dev have not yet been updated because they
are assigned only after every transfer has been mapped. The subsequent
spi_unmap_msg() may therefore unmap the TX mapping again or release
earlier mappings using a NULL or stale device. Using a NULL device can
trigger an oops. An empty SG table does not prevent the NULL dereference
because dma_unmap_sg_attrs() accesses the device before checking the
entry count.

Publish both mapping devices before mapping starts and unwind all
failures through __spi_unmap_msg(). This clears the mapping flags and
releases each mapping once with the device that created it.

Publishing the devices before the loop also refreshes them when no
transfer needs mapping. No mapping flag is set in that case, so current
users do not use the pointers as mapping owners.

## Which versions are affected by CVE-2026-90012?


## How do I fix CVE-2026-90012?

Apply the vendor's patch.

## Is CVE-2026-90012 being exploited?

There is no known exploitation of CVE-2026-90012 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90012 and fix it if it is affected.

What it is: CVE-2026-90012 is a critical vulnerability in Linux, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90012 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-2026-90012/ (Markdown: https://insights.sbomify.com/CVE-2026-90012/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90012
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90012
- OSV: https://osv.dev/vulnerability/CVE-2026-90012

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90012/
Summaries are generated and may contain mistakes; the official description above is the record.