Linux Kernel up to 6.6.84/6.12.20/6.13.8 dma_fence_add_callback reference count

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.6.84/6.12.20/6.13.8 and classified as critical. Affected by this issue is the function dma_fence_add_callback. Performing a manipulation results in reference count. This vulnerability is reported as CVE-2025-21995. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.84/6.12.20/6.13.8. It has been classified as critical. This affects the function dma_fence_add_callback. The manipulation with an unknown input leads to a reference count vulnerability. CWE is classifying the issue as CWE-911. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: drm/sched: Fix fence reference count leak The last_scheduled fence leaks when an entity is being killed and adding the cleanup callback fails. Decrement the reference count of prev when dma_fence_add_callback() fails, ensuring proper balance. [phasta: add git tag info for stable kernel]

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2025-21995 since 12/29/2024. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 241070 (Ubuntu 24.04 LTS : Linux kernel (OEM) vulnerabilities (USN-7606-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.85, 6.12.21 or 6.13.9 eliminates this vulnerability. Applying the patch c76bd3c99293834de7d1dca5de536616d5655e38/1135a9431160575466ea9ac37ebd756ecbe35fff/35399c84dcedd6d31448fb9e1336ef52673f2882/a952f1ab696873be124e31ce5ef964d36bce817f 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 (241070) and CERT Bund (WID-SEC-2025-0698). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• Open Source Linux Kernel
• SolarWinds Security Event Manager
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 6.6.10
• 6.6.11
• 6.6.12
• 6.6.13
• 6.6.14
• 6.6.15
• 6.6.16
• 6.6.17
• 6.6.18
• 6.6.19
• 6.6.20
• 6.6.21
• 6.6.22
• 6.6.23
• 6.6.24
• 6.6.25
• 6.6.26
• 6.6.27
• 6.6.28
• 6.6.29
• 6.6.30
• 6.6.31
• 6.6.32
• 6.6.33
• 6.6.34
• 6.6.35
• 6.6.36
• 6.6.37
• 6.6.38
• 6.6.39
• 6.6.40
• 6.6.41
• 6.6.42
• 6.6.43
• 6.6.44
• 6.6.45
• 6.6.46
• 6.6.47
• 6.6.48
• 6.6.49
• 6.6.50
• 6.6.51
• 6.6.52
• 6.6.53
• 6.6.54
• 6.6.55
• 6.6.56
• 6.6.57
• 6.6.58
• 6.6.59
• 6.6.60
• 6.6.61
• 6.6.62
• 6.6.63
• 6.6.64
• 6.6.65
• 6.6.66
• 6.6.67
• 6.6.68
• 6.6.69
• 6.6.70
• 6.6.71
• 6.6.72
• 6.6.73
• 6.6.74
• 6.6.75
• 6.6.76
• 6.6.77
• 6.6.78
• 6.6.79
• 6.6.80
• 6.6.81
• 6.6.82
• 6.6.83
• 6.6.84
• 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
• 6.13.0
• 6.13.1
• 6.13.2
• 6.13.3
• 6.13.4
• 6.13.5
• 6.13.6
• 6.13.7
• 6.13.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

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