CVE-2026-64073

Description

In the Linux kernel, the following vulnerability has been resolved: irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT On PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via run_irq_workd(), so irq_work_sync() uses rcuwait() to wait for BUSY==0. After irq_work_single() clears BUSY via atomic_cmpxchg(), it still dereferences @work for irq_work_is_hard() and rcuwait_wake_up(). An irq_work_sync() caller on another CPU that enters after BUSY is cleared can observe BUSY==0 immediately, return, and free the work before those accesses complete — causing a use-after-free. Fix this by wrapping run_irq_workd() in guard(rcu)() so that the entire irq_work_single() execution is within an RCU read-side critical section. Then add synchronize_rcu() in irq_work_sync() after rcuwait_wait_event() to ensure the caller waits for the RCU grace period before returning, preventing premature frees.

References

• https://git.kernel.org/stable/c/18c0456ea2615b1a743a6db739c74411c3b42bc6
• https://git.kernel.org/stable/c/2dc79362302922cb18f35e262712b5e58de65442
• https://git.kernel.org/stable/c/684a78183c54c23e70d1cba320f7fc184604210b
• https://git.kernel.org/stable/c/81b582784518196eff1050212a046bc29d3a05dd
• https://git.kernel.org/stable/c/91840be8f710370607f949a627e070896faeddb8