CVE-2024-27009: s390/cio: fix race condition during online processing

Severity: medium (CVSS 4.7 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: 2024-05-01 · updated 2026-06-17
Weakness: CWE-362

Description

In the Linux kernel, the following vulnerability has been resolved: s390/cio: fix race condition during online processing A race condition exists in ccw_device_set_online() that can cause the online process to fail, leaving the affected device in an inconsistent state. As a result, subsequent attempts to set that device online fail with return code ENODEV. The problem occurs when a path verification request arrives after a wait for final device state completed, but before the result state is evaluated. Fix this by ensuring that the CCW-device lock is held between determining final state and checking result state. Note that since: commit 2297791c92d0 ("s390/cio: dont unregister subchannel from child-drivers") path verification requests are much more likely to occur during boot, resulting in an increased chance of this race condition occurring.

Affected products

Linux kernel: from 5.15 before 5.15.157; from 5.16 before 6.1.88; from 6.2 before 6.6.29; from 6.7 before 6.8.8; 6.9-rc1, 6.9-rc2, 6.9-rc3, 6.9-rc4 — fixed in 5.15.157, 6.1.88, 6.6.29, 6.8.8

How to fix

Upgrade to a fixed version: Linux kernel 5.15.157, 6.1.88, 6.6.29, 6.8.8. Check the vendor advisory for mitigations.

References

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