Linux Kernel up to 6.18-rc1 drm_sched_job_add_dependency double free

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.1.157/6.6.113/6.12.54/6.17.4/6.18-rc1. This affects the function drm_sched_job_add_dependency. The manipulation results in double free. This vulnerability is reported as CVE-2025-40096. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.1.157/6.6.113/6.12.54/6.17.4/6.18-rc1. Affected is the function drm_sched_job_add_dependency. The manipulation with an unknown input leads to a double free vulnerability. CWE is classifying the issue as CWE-415. The product calls free() twice on the same memory address, potentially leading to modification of unexpected memory locations. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: drm/sched: Fix potential double free in drm_sched_job_add_resv_dependencies When adding dependencies with drm_sched_job_add_dependency(), that function consumes the fence reference both on success and failure, so in the latter case the dma_fence_put() on the error path (xarray failed to expand) is a double free. Interestingly this bug appears to have been present ever since commit ebd5f74255b9 ("drm/sched: Add dependency tracking"), since the code back then looked like this: drm_sched_job_add_implicit_dependencies(): ... for (i = 0; i < fence_count; i++) { ret = drm_sched_job_add_dependency(job, fences[i]); if (ret) break; } for (; i < fence_count; i++) dma_fence_put(fences[i]); Which means for the failing 'i' the dma_fence_put was already a double free. Possibly there were no users at that time, or the test cases were insufficient to hit it. The bug was then only noticed and fixed after commit 9c2ba265352a ("drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2") landed, with its fixup of commit 4eaf02d6076c ("drm/scheduler: fix drm_sched_job_add_implicit_dependencies"). At that point it was a slightly different flavour of a double free, which commit 963d0b356935 ("drm/scheduler: fix drm_sched_job_add_implicit_dependencies harder") noticed and attempted to fix. But it only moved the double free from happening inside the drm_sched_job_add_dependency(), when releasing the reference not yet obtained, to the caller, when releasing the reference already released by the former in the failure case. As such it is not easy to identify the right target for the fixes tag so lets keep it simple and just continue the chain. While fixing we also improve the comment and explain the reason for taking the reference and not dropping it.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2025-40096 since 04/16/2025. The exploitability is told to be difficult. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 02/16/2026).

The vulnerability scanner Nessus provides a plugin with the ID 272063 (Linux Distros Unpatched Vulnerability : CVE-2025-40096), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.158, 6.6.114, 6.12.55, 6.17.5 or 6.18-rc2 eliminates this vulnerability. Applying the patch 4c38a63ae12ecc9370a7678077bde2d61aa80e9c/57239762aa90ad768dac055021f27705dae73344/e5e3eb2aff92994ee81ce633f1c4e73bd4b87e11/fdfb47e85af1e11ec822c82739dde2dd8dff5115/5801e65206b065b0b2af032f7f1eef222aa2fd83 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (272063) and CERT Bund (WID-SEC-2025-2450). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel
• Dell NetWorker

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.157
• 6.6.113
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.12.53
• 6.12.54
• 6.17.0
• 6.17.1
• 6.17.2
• 6.17.3
• 6.17.4
• 6.18-rc1

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

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