SB20261023244 - Improper locking in Linux kernel s390 kvm

Description

This security bulletin contains information about 1 vulnerability.

1) Improper locking (CVE-ID: CVE-2026-98930)

CWE-ID: CWE-667 - Improper Locking

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to potentially cause a denial of service.

The vulnerability exists due to improper locking in the Linux kernel's s390 KVM interrupt handling when processing a SIGP Stop and Store Status operation for an already stopped vCPU. A local user can trigger a status-store operation that writes to userspace while a spinlock is held, allowing a page fault to require blocking in an atomic context and potentially cause a denial of service.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/3bd77c59576b1d447fd56cc689ae9523a334b924
• https://git.kernel.org/stable/c/a379ac504fcb8c6fc2aa36203f5489b9581eb2e0
• https://git.kernel.org/stable/c/d0e3bf633f0585a0c2c2105ea7723777d764fae5
• https://git.kernel.org/stable/c/d343407b728a80b74be3c24b59f15e60289ea527