In the Linux kernel, the following vulnerability has been resolved: sched_ext: Build the cid tables privately and publish them with RCU The cid… (CVE-2026-98942)

The Linux kernel sched_ext vulnerability involved the cid tables being visible to cid kfuncs during modification, leading to potential race conditions where tracing or syscall programs could read uninitialized or inconsistent memory. The root cause was that global pointers to cid tables were published before the tables were fully built, and some functions accessed these tables without proper RCU or preemption protection. The fix ties the lifetime of cid tables to the root scheduler, building fresh tables privately and publishing them only after finalization. It also adds proper synchronization and NULL checks in kfuncs to ensure safe access, preventing exposure of uninitialized memory and torn updates.

Exploitation could allow a racing tracing or syscall program to read uninitialized kernel memory or inconsistent data structures related to the scheduler's cid tables. This could potentially lead to information disclosure of kernel memory contents. There is no indication of code execution or privilege escalation from the provided data.

A fix has been implemented in the Linux kernel to address this vulnerability by changing how cid tables are built and published with proper synchronization and RCU protection. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; check the vendor advisory or Linux kernel mailing lists for the official patch and update guidance.