bpf: Fix mmap_lock deadlock on arena lock failure

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Summary

CVECVE-2026-90342
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 17:17:32 UTC
Updated2026-09-17 17:17:32 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Fix mmap_lock deadlock on arena lock failure Reported by the Sashiko AI review. arena_vm_fault() returns VM_FAULT_RETRY when it can't take arena->spinlock, but it never took mmap_lock. The fault path assumes a VM_FAULT_RETRY handler already dropped mmap_lock and re-takes it on the retry, so mmap_lock gets taken twice and can deadlock: do_user_addr_fault() { fault = handle_mm_fault(...); // calls arena_vm_fault() if (fault & VM_FAULT_RETRY) goto retry; // re-locks mmap_lock mmap_read_unlock(mm); } Return VM_FAULT_SIGBUS instead, for two reasons: 1. We could keep VM_FAULT_RETRY, but then we'd have to drop the fault lock first and cap the retry ourselves, the way __folio_lock_or_retry() does. 2. A failed raw_res_spin_lock_irqsave() already means a possible deadlock was detected, so retrying just hits the same lock again. So returning VM_FAULT_RETRY here is overkill.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b8467290edab4bafae352bf3f317055669a1a458 af8087f16714f7620c4db3e732baaa1b2337948f git Not specified
CNA Linux Linux affected b8467290edab4bafae352bf3f317055669a1a458 0b10b945479c954393d62ee3229d2f224a4ca91c git Not specified
CNA Linux Linux affected 7.0 Not specified
CNA Linux Linux unaffected 7.0 semver Not specified
CNA Linux Linux unaffected 7.2.6 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/af8087f16714f7620c4db3e732baaa1b2337948f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0b10b945479c954393d62ee3229d2f224a4ca91c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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