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| author | Sean Christopherson <seanjc@google.com> | 2024-02-27 18:41:47 -0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2024-05-07 11:59:24 -0400 |
| commit | 2b1f435505aee67094a9427ebc27ac04842d9f95 (patch) | |
| tree | 27b5b43c2d304d503ee79de0271aead0d2820b24 /arch/x86 | |
| parent | f3310e622f77979f13a36f6bfaf0252eecc7b9f6 (diff) | |
| download | linux-stable-2b1f435505aee67094a9427ebc27ac04842d9f95.tar.gz linux-stable-2b1f435505aee67094a9427ebc27ac04842d9f95.tar.bz2 linux-stable-2b1f435505aee67094a9427ebc27ac04842d9f95.zip | |
KVM: x86/mmu: Sanity check that __kvm_faultin_pfn() doesn't create noslot pfns
WARN if __kvm_faultin_pfn() generates a "no slot" pfn, and gracefully
handle the unexpected behavior instead of continuing on with dangerous
state, e.g. tdp_mmu_map_handle_target_level() _only_ checks fault->slot,
and so could install a bogus PFN into the guest.
The existing code is functionally ok, because kvm_faultin_pfn() pre-checks
all of the cases that result in KVM_PFN_NOSLOT, but it is unnecessarily
unsafe as it relies on __gfn_to_pfn_memslot() getting the _exact_ same
memslot, i.e. not a re-retrieved pointer with KVM_MEMSLOT_INVALID set.
And checking only fault->slot would fall apart if KVM ever added a flag or
condition that forced emulation, similar to how KVM handles writes to
read-only memslots.
Cc: David Matlack <dmatlack@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Message-ID: <20240228024147.41573-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index f5e13f8a67c0..5ae0f2f503b4 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4424,7 +4424,7 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, if (unlikely(is_error_pfn(fault->pfn))) return kvm_handle_error_pfn(vcpu, fault); - if (WARN_ON_ONCE(!fault->slot)) + if (WARN_ON_ONCE(!fault->slot || is_noslot_pfn(fault->pfn))) return kvm_handle_noslot_fault(vcpu, fault, access); /* |