CVE-2026-64287KVM: arm64: Bound used_lrs when flushing the pKVM hyp vCPU

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/2c5e72b9fbf83fdfa724e9f1af0f418ccf8739b8
• https://git.kernel.org/stable/c/9fa301d8298778dd799fa4dcf7a7f440715d146e
• https://git.kernel.org/stable/c/c646431865f4b1a5b14067233fa27b11e05e0d46
• https://git.kernel.org/stable/c/7fca3fcef81c713bc82a37bf741e0f28e6d04a6f
• https://git.kernel.org/stable/c/8cc8bbbfab14c22c5551d0dd19b208a44b141c76