CVE-2026-89917

CVE CVE-2026-89917EUVD EUVD-2026-80517Published 2026-09-16T10:32:12.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Handle VNCR TLB invalidation race with vcpu_put() VNCR unmapping While VNCR TLB invalidation always occurs under the MMU lock, vcpu_put() doesn't, while it unmaps the VNCR page. The problem is that the invalidation evaluates vncr_tlb::cpu to decide whether an unmapping needs to take place (cpu != -1) before performing it. On the other hand, this_cpu_reset_vncr_fixmap() unconditionally unmaps if L1_VNCR_MAPPED is set. These two obviously can race, with a TOCTOU pattern on the TLBI path, and a BUG_ON() on the vcpu_put() path. And the two can end-up calling vncr_fixmap(-1), with extra lethal effects. Move the reset of vncr_tlb::cpu to -1 to a common function, and make this update atomic so that only a single thread can reset the field and perform the corresponding unmap. The vcpu_put() still need to unconditionally unmap the current VNCR to close another ugly race. Finally, the assignment of vncr_tlb::cpu is moved to be kept in sync with the actual mapping, similar to L1_VNCR_MAPPED being set.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux 7270cc9157f474dfc46750a34c9d7defc686b2eb <9065c1261f8a05c6a7a2d90048c7c0665ab2896d; patch: 6.18.52; 6.16; patch: 7.3-rc1; 7270cc9157f474dfc46750a34c9d7defc686b2eb <5cbd8761d001c11ada73b1753d772c4745a70e72; patch: 7.2.5; patch: 0; 7270cc9157f474dfc46750a34c9d7defc686b2eb <38640bc32be3fcf9526d477155bc19d3f146231f

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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