SB20261022106 - Deadlock in Linux kernel kernel/kprobes.c: wait_for_kprobe_optimizer_locked() and kprobe_optimizer()

Description

This security bulletin contains information about 1 vulnerability.

1) Deadlock (CVE-ID: CVE-2026-98530)

CWE-ID: CWE-833 - Deadlock

CVSSv4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

The vulnerability allows a local privileged user to cause a denial of service by permanently blocking kprobe optimizer flush operations and subsequent access to the kprobes optimization sysctl.

The vulnerability exists due to improper synchronization in the Linux kernel kprobe optimizer when flushing optimization work. A local privileged user can write 0 to /proc/sys/debug/kprobes-optimization while a kprobe is jump-optimized to leave the writer waiting indefinitely while holding kprobe_sysctl_mutex, blocking subsequent reads and writes to that sysctl. The optimizer incorrectly signals completion only when the completion is already done, and concurrent flushers can also reinitialize the shared completion and remove an existing waiter from its wait queue.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/5bfa9f1a9dcb6ecb607adbc1c0226605c972935b
• https://git.kernel.org/stable/c/f05a01fc7d4f731b4c100d2aef1e85ad77728862