From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
commit 9f46c187e2e680ecd9de7983e4d081c3391acc76 upstream.
With shadow paging enabled, the INVPCID instruction results in a call
to kvm_mmu_invpcid_gva. If INVPCID is executed with CR0.PG=0, the
invlpg callback is not set and the result is a NULL pointer dereference.
Fix it trivially by checking for mmu->invlpg before every call.
There are other possibilities:
- check for CR0.PG, because KVM (like all Intel processors after P5)
flushes guest TLB on CR0.PG changes so that INVPCID/INVLPG are a
nop with paging disabled
- check for EFER.LMA, because KVM syncs and flushes when switching
MMU contexts outside of 64-bit mode
All of these are tricky, go for the simple solution. This is CVE-2022-1789.
Reported-by: Yongkang Jia <kangel@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
[fix conflict due to missing b9e5603c2a3accbadfec570ac501a54431a6bdba]
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index e7cd16e1e0a0b..ff65584c7e5f4 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5416,14 +5416,16 @@ void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid)
uint i;
if (pcid == kvm_get_active_pcid(vcpu)) {
- mmu->invlpg(vcpu, gva, mmu->root_hpa);
+ if (mmu->invlpg)
+ mmu->invlpg(vcpu, gva, mmu->root_hpa);
tlb_flush = true;
}
for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) {
if (VALID_PAGE(mmu->prev_roots[i].hpa) &&
pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) {
- mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
+ if (mmu->invlpg)
+ mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa);
tlb_flush = true;
}
}
--
2.35.1.46.g38062e73e0
