CVE-2026-90247
bpf: Fix mmap_lock leak in irq_work path
Description
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.
INFO
Published Date :
Sept. 17, 2026, 5:17 p.m.
Last Modified :
Sept. 17, 2026, 5:17 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Reserve per-CPU slot before mmap_read_trylock.
- Use same wrapper in stackmap and bpf_find_vma.
- Release reservation on trylock failure.
- Release slot after irq_work callback unlocks mm.
References to Advisories, Solutions, and Tools
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CVE-2026-90247.
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associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
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weaknesses.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Sep. 17, 2026
Action Type Old Value New Value Added Description 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. Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/90xxx/CVE-2026-90247.json">CVE-2026-90247</a> Added Reference https://git.kernel.org/stable/c/051f2da26ce377f683b938a3382e0f16d02f3139 Added Reference https://git.kernel.org/stable/c/a052ad5edccf5319f50ed955de4368f8318a9f20 Added Reference https://git.kernel.org/stable/c/fa9dcacdcdf487f0ffef64bf67622f1caed509f1