CVE-2026-98863KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails

Official description

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails Re-pend GET_NESTED_STATE_PAGES before exiting to userspace if getting the nested pages fails in the KVM_RUN path. If userspace re-runs the vCPU, and vmcs02 holds valid PFNs from the *previous* run of L2, then KVM could re-enter L2 with stale, unpinned PFNs mapped into e.g. the vAPIC page. Note, both SVM and VMX (as of commit 11722439fb20 ("KVM: nVMX: Ensure KVM_REQ_GET_NESTED_STATE_PAGES is cleared on VM-Exit") ensure the request is cleared on VM-Exit (including the "forced" case), i.e. there is no risk of double-mapping due to emulated VMLAUNCH/VMRESUME/VMRUN *and* the request trying to map the nested pages.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/525694a6021ec6c8f7ce1f38acdf2dd77698fec1
• https://git.kernel.org/stable/c/942192dbcd3a06695ef6b31cf10a41a21cf014d8
• https://git.kernel.org/stable/c/10180a277549339020b08000206092c07e0bff5a