Description
In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE When installing an emulated MMIO SPTE, do so *after* dropping/zapping the existing SPTE (if it's shadow-present). While commit a54aa15c6bda3 was right about it being impossible to convert a shadow-present SPTE to an MMIO SPTE due to a _guest_ write, it failed to account for writes to guest memory that are outside the scope of KVM. E.g. if host userspace modifies a shadowed gPTE to switch from a memslot to emulted MMIO and then the guest hits a relevant page fault, KVM will install the MMIO SPTE without first zapping the shadow-present SPTE. ------------[ cut here ]------------ is_shadow_present_pte(*sptep) WARNING: arch/x86/kvm/mmu/mmu.c:484 at mark_mmio_spte+0xb2/0xc0 [kvm], CPU#0: vmx_ept_stale_r/4292 Modules linked in: kvm_intel kvm irqbypass CPU: 0 UID: 1000 PID: 4292 Comm: vmx_ept_stale_r Not tainted 7.0.0-rc2-eafebd2d2ab0-sink-vm #319 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:mark_mmio_spte+0xb2/0xc0 [kvm] Call Trace: <TASK> mmu_set_spte+0x237/0x440 [kvm] ept_page_fault+0x535/0x7f0 [kvm] kvm_mmu_do_page_fault+0xee/0x1f0 [kvm] kvm_mmu_page_fault+0x8d/0x620 [kvm] vmx_handle_exit+0x18c/0x5a0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xc55/0x1c20 [kvm] kvm_vcpu_ioctl+0x2d5/0x980 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb5/0x730 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x47fa3f </TASK> ---[ end trace 0000000000000000 ]---
Product status
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f (git) before 20656cd1f243d3a154aac5dd1b823110b6906fe1
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f (git) before ed5909992f344a7d3f4024261e9f751d9618a27d
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f (git) before fd28c5618699180cd69619801e9ae6a5266c0a22
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f (git) before 459158151a158a6703b49f3c9de0e536d8bd553f
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f (git) before 695320de6eadb75aaed8be1787c4ce4c189e4c7b
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f (git) before bce7fe59d43531623f3e43779127bfb33804925d
a54aa15c6bda3ca7e2f9e040ba968a1da303e24f (git) before aad885e774966e97b675dfe928da164214a71605
5.13
Any version before 5.13
5.15.203 (semver)
6.1.168 (semver)
6.6.131 (semver)
6.12.80 (semver)
6.18.21 (semver)
6.19.11 (semver)
7.0 (original_commit_for_fix)
References
git.kernel.org/...c/20656cd1f243d3a154aac5dd1b823110b6906fe1
git.kernel.org/...c/ed5909992f344a7d3f4024261e9f751d9618a27d
git.kernel.org/...c/fd28c5618699180cd69619801e9ae6a5266c0a22
git.kernel.org/...c/459158151a158a6703b49f3c9de0e536d8bd553f
git.kernel.org/...c/695320de6eadb75aaed8be1787c4ce4c189e4c7b
git.kernel.org/...c/bce7fe59d43531623f3e43779127bfb33804925d
git.kernel.org/...c/aad885e774966e97b675dfe928da164214a71605