CVE-2026-64073

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux810979682ccc98dbd83f341c18a2e556c30a7164 < 2dc79362302922cb18f35e262712b5e58de65442affected
LinuxLinux810979682ccc98dbd83f341c18a2e556c30a7164 < eef4f71b46a9929ac33e968538c9dd5d96a02460affected
LinuxLinux810979682ccc98dbd83f341c18a2e556c30a7164 < 684a78183c54c23e70d1cba320f7fc184604210baffected
LinuxLinux810979682ccc98dbd83f341c18a2e556c30a7164 < 18c0456ea2615b1a743a6db739c74411c3b42bc6affected
LinuxLinux810979682ccc98dbd83f341c18a2e556c30a7164 < 81b582784518196eff1050212a046bc29d3a05ddaffected
LinuxLinux810979682ccc98dbd83f341c18a2e556c30a7164 < 91840be8f710370607f949a627e070896faeddb8affected
LinuxLinux5.16affected
LinuxLinux0 < 5.16unaffected
LinuxLinux6.1.175 <= 6.1.*unaffected
LinuxLinux6.6.142 <= 6.6.*unaffected
LinuxLinux6.12.92 <= 6.12.*unaffected
LinuxLinux6.18.34 <= 6.18.*unaffected
LinuxLinux7.0.11 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References