# CVE-2024-26940: drm/vmwgfx: Create debugfs ttm_resource_manager entry only if needed

> A null pointer dereference in the vmwgfx driver causes a kernel crash when reading debugfs entries if the resource manager is not allocated.

- **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:** 1 May 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2024-26940, DEBIAN-CVE-2024-26940, GHSA-cfg9-pfwm-v8pc, UBUNTU-CVE-2024-26940

## What is CVE-2024-26940?

CVE-2024-26940 is a medium-severity vulnerability in Linux kernel, published on 1 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:

drm/vmwgfx: Create debugfs ttm_resource_manager entry only if needed

The driver creates /sys/kernel/debug/dri/0/mob_ttm even when the
corresponding ttm_resource_manager is not allocated.
This leads to a crash when trying to read from this file.

Add a check to create mob_ttm, system_mob_ttm, and gmr_ttm debug file
only when the corresponding ttm_resource_manager is allocated.

crash> bt
PID: 3133409  TASK: ffff8fe4834a5000  CPU: 3    COMMAND: "grep"
 #0 [ffffb954506b3b20] machine_kexec at ffffffffb2a6bec3
 #1 [ffffb954506b3b78] __crash_kexec at ffffffffb2bb598a
 #2 [ffffb954506b3c38] crash_kexec at ffffffffb2bb68c1
 #3 [ffffb954506b3c50] oops_end at ffffffffb2a2a9b1
 #4 [ffffb954506b3c70] no_context at ffffffffb2a7e913
 #5 [ffffb954506b3cc8] __bad_area_nosemaphore at ffffffffb2a7ec8c
 #6 [ffffb954506b3d10] do_page_fault at ffffffffb2a7f887
 #7 [ffffb954506b3d40] page_fault at ffffffffb360116e
    [exception RIP: ttm_resource_manager_debug+0x11]
    RIP: ffffffffc04afd11  RSP: ffffb954506b3df0  RFLAGS: 00010246
    RAX: ffff8fe41a6d1200  RBX: 0000000000000000  RCX: 0000000000000940
    RDX: 0000000000000000  RSI: ffffffffc04b4338  RDI: 0000000000000000
    RBP: ffffb954506b3e08   R8: ffff8fee3ffad000   R9: 0000000000000000
    R10: ffff8fe41a76a000  R11: 0000000000000001  R12: 00000000ffffffff
    R13: 0000000000000001  R14: ffff8fe5bb6f3900  R15: ffff8fe41a6d1200
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #8 [ffffb954506b3e00] ttm_resource_manager_show at ffffffffc04afde7 [ttm]
 #9 [ffffb954506b3e30] seq_read at ffffffffb2d8f9f3
    RIP: 00007f4c4eda8985  RSP: 00007ffdbba9e9f8  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 000000000037e000  RCX: 00007f4c4eda8985
    RDX: 000000000037e000  RSI: 00007f4c41573000  RDI: 0000000000000003
    RBP: 000000000037e000   R8: 0000000000000000   R9: 000000000037fe30
    R10: 0000000000000000  R11: 0000000000000246  R12: 00007f4c41573000
    R13: 0000000000000003  R14: 00007f4c41572010  R15: 0000000000000003
    ORIG_RAX: 0000000000000000  CS: 0033  SS: 002b

## Which versions are affected by CVE-2024-26940?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-26940?

Apply the vendor's patch.

## Is CVE-2024-26940 being exploited?

There is no known exploitation of CVE-2024-26940 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-2024-26940 and fix it if it is affected.

What it is: CVE-2024-26940 is a medium-severity vulnerability in Linux kernel, published on 1 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-2024-26940 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-2024-26940/ (Markdown: https://insights.sbomify.com/CVE-2024-26940/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26940
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26940
- OSV: https://osv.dev/vulnerability/CVE-2024-26940

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26940/
Summaries are generated and may contain mistakes; the official description above is the record.