CVE-2026-90247

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/a052ad5edccf5319f50ed955de4368f8318a9f20
• https://git.kernel.org/stable/c/051f2da26ce377f683b938a3382e0f16d02f3139
• https://git.kernel.org/stable/c/fa9dcacdcdf487f0ffef64bf67622f1caed509f1

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