KVM: arm64: Bound used_lrs when flushing the pKVM hyp vCPU

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Bound used_lrs when flushing the pKVM hyp vCPU flush_hyp_vcpu() copies the host vGIC state into the hyp's private vCPU on every run. The vGIC list register save and restore use used_lrs as their loop bound and expect it to stay within the number of implemented list registers. While this is generally the case, flush_hyp_vcpu() copies vgic_v3 verbatim and does not enforce this, so a value provided by the host is used at EL2 to index vgic_lr[] and access ICH_LR<n>_EL2 (host -> EL2). Fix by clamping used_lrs to the number of implemented list registers after the copy, as the trusted path already does in vgic_flush_lr_state(). The number of implemented list registers is constant after init, so it is replicated once from kvm_vgic_global_state.nr_lr into hyp_gicv3_nr_lr rather than read on every entry.

Timeline

1. Jul 25, 2026, 8:49 AM UTCCVE published
2. Oct 16, 2026, 3:38 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 19, 2026, 8:38 PM UTCRecord last updated

Affected versions

• Linux Linux

  From be66e67f175096f283c9d5614c4991fc9e7ed975 · fixed in 2c5e72b9fbf83fdfa724e9f1af0f418ccf8739b8; From be66e67f175096f283c9d5614c4991fc9e7ed975 · fixed in 9fa301d8298778dd799fa4dcf7a7f440715d146e; From be66e67f175096f283c9d5614c4991fc9e7ed975 · fixed in c646431865f4b1a5b14067233fa27b11e05e0d46; From be66e67f175096f283c9d5614c4991fc9e7ed975 · fixed in 7fca3fcef81c713bc82a37bf741e0f28e6d04a6f; From be66e67f175096f283c9d5614c4991fc9e7ed975 · fixed in 8cc8bbbfab14c22c5551d0dd19b208a44b141c76

• Linux Linux

  6.2

• KernelLinux

  From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.4

References 5