CVE-2026-89516

In the Linux kernel, the following vulnerability has been resolved:

sched ext: Don't BUG ON a destroyed DSQ in process deferred reenq users

scx bpf dsq reenq() queues a deferred reenq (dru) that runs from run deferred(), not ops.dispatch(). If the DSQ is destroyed before the dru runs, process deferred reenq users() sees dsq->id == SCX DSQ INVALID and hits the BUG ON. destroy dsq() doesn't flush pending drus, so just skip.

tj: Read dsq->id once with READ ONCE(). Reading it separately in the INVALID check and the BUG ON would leave a window where destroy dsq() can invalidate the id between the two reads and still trigger the BUG ON.