CVE-2026-90247

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

bpf: Fix mmap_lock leak in irq_work path

stack_map_get_build_id_offset() introduced a per-CPU irq_work to defer

mmap_read_unlock() from NMI context, and bpf_find_vma() later reused the

same mmap_unlock_work. Both callers only check whether the work is busy

before taking mmap_lock, so a nested caller can reuse the slot before the

first caller queues it. Two read locks may then be acquired while only one

deferred unlock runs, leaking a read lock and blocking exit_mmap().

Reserve the per-CPU slot before mmap_read_trylock(). Use the same wrapper

in stackmap and bpf_find_vma() so both callers release the reservation on

trylock failure. Keep rejecting the slot while the irq_work remains busy.

Release it after the irq_work callback unlocks the mm.