CVE-2026-89918: KVM: arm64: Correctly handle end of VA space TLBI invalidation
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Correctly handle end of VA space TLBI invalidation
Our TLB invalidation by VA code is based on comparing two ranges, one defined by the TLB, and one defined by the TLBI instruction.
Each range is defined by a start and a size. However, the way the comparison is done doesn't account for address rollover, as it compares an address with (base + size). This works nicely until this expression represent the last page/block in the TTBR1 VA space, as the result is a big fat 0. And a failed TLB invalidation.
Rewrite the comparison in a way that is immune to the address rollover (making the end address inclusive instead of exclusive), and move this into a common helper that is used by both VA and IPA invalidations, as suggested by Hyunwoo Kim (although the IPA version didn't suffer from this particular problem, obviously).
Affected Software
Event History
Frequently Asked Questions
Which systems are exposed to this issue?
The issue affects the Linux kernel's KVM implementation on arm64. It is relevant where KVM performs TLB invalidation by virtual address and the invalidated range reaches the final page or block of the TTBR1 virtual-address space.
What is the practical failure mode?
A virtual-address TLB invalidation can fail because the range comparison wraps when calculating base plus size at the end of the TTBR1 VA space. This can leave TLB entries that should have been invalidated.
How can I determine whether a kernel includes the fix?
Check whether the kernel contains one of the referenced stable commits: ce447651a52ec077694172af10c4fffb11f56c43, c624731ca6fe59ad8909ce4108301aa7560a91d6, or 34af2c3e31f91a739dc175459fdbd99ed952b457. The fix changes the range comparison to use an inclusive end address and shares the helper with IPA invalidation handling.