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CVE-2025-40242: gfs2: Fix unlikely race in gdlm_put_lock

• Severity: high (CVSS 7.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-12-04 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix unlikely race in gdlm_put_lock In gdlm_put_lock(), there is a small window of time in which the DFL_UNMOUNT flag has been set but the lockspace hasn't been released, yet. In that window, dlm may still call gdlm_ast() and gdlm_bast(). To prevent it from dereferencing freed glock objects, only free the glock if the lockspace has actually been released.

Affected products

• Linux kernel: from 4.4.284 before 4.5; from 4.9.283 before 4.10; from 4.14.247 before 4.15; from 4.19.207 before 4.20; from 5.4.148 before 5.5; from 5.10.67 before 5.11 — fixed in 4.10, 4.15, 4.20, 4.5, 5.11, 5.14

How to fix

Upgrade to a fixed version: Linux kernel 4.10, 4.15, 4.20, 4.5. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/279bde3bbb0ac0bad5c729dfa85983d75a5d7641
• https://git.kernel.org/stable/c/28c4d9bc0708956c1a736a9e49fee71b65deee81
• https://git.kernel.org/stable/c/4913592a3358f6ec366b8346b733d5e2360b08e1
• https://git.kernel.org/stable/c/5fdc1474e678eea1700aa266c0b7c2c96f81dd0d
• https://git.kernel.org/stable/c/64c61b4ac645222fa7b724cef616c1f862a72a40

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