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CVE-2025-21856: s390/ism: add release function for struct device

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-03-12 · updated 2026-06-17
• Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: s390/ism: add release function for struct device According to device_release() in /drivers/base/core.c, a device without a release function is a broken device and must be fixed. The current code directly frees the device after calling device_add() without waiting for other kernel parts to release their references. Thus, a reference could still be held to a struct device, e.g., by sysfs, leading to potential use-after-free issues if a proper release function is not set.

Affected products

• Linux kernel: from 6.3 before 6.6.80; from 6.7 before 6.12.17; from 6.13 before 6.13.5; 6.14-rc1, 6.14-rc2, 6.14-rc3 — fixed in 6.12.17, 6.13.5, 6.6.80

How to fix

Upgrade to a fixed version: Linux kernel 6.12.17, 6.13.5, 6.6.80. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0505ff2936f166405d81d0d454a81d9c14124344
• https://git.kernel.org/stable/c/915e34d5ad35a6a9e56113f852ade4a730fb88f0
• https://git.kernel.org/stable/c/940d15254d2216b585558bcf36312da50074e711
• https://git.kernel.org/stable/c/e26e8ac27351f457091459a0a355bacd06d5bb2b

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