MIPS: KVM: Add missing gfn range check

kvm_mips_handle_mapped_seg_tlb_fault() calculates the guest frame number
based on the guest TLB EntryLo values, however it is not range checked
to ensure it lies within the guest_pmap. If the physical memory the
guest refers to is out of range then dump the guest TLB and emit an
internal error.

Fixes: 858dd5d45733 ("KVM/MIPS32: MMU/TLB operations for the Guest.")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org> # 3.10.x-
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index 96e0b24..701c1b6 100644 (file)
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -138,6 +138,7 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
        unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
        struct kvm *kvm = vcpu->kvm;
        kvm_pfn_t pfn0, pfn1;
+       gfn_t gfn0, gfn1;
        long tlb_lo[2];
        int ret;
 
@@ -152,18 +153,24 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
                        VPN2_MASK & (PAGE_MASK << 1)))
                tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;
 
-       if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[0])
-                                  >> PAGE_SHIFT) < 0)
+       gfn0 = mips3_tlbpfn_to_paddr(tlb_lo[0]) >> PAGE_SHIFT;
+       gfn1 = mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT;
+       if (gfn0 >= kvm->arch.guest_pmap_npages ||
+           gfn1 >= kvm->arch.guest_pmap_npages) {
+               kvm_err("%s: Invalid gfn: [%#llx, %#llx], EHi: %#lx\n",
+                       __func__, gfn0, gfn1, tlb->tlb_hi);
+               kvm_mips_dump_guest_tlbs(vcpu);
+               return -1;
+       }
+
+       if (kvm_mips_map_page(kvm, gfn0) < 0)
                return -1;
 
-       if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb_lo[1])
-                                  >> PAGE_SHIFT) < 0)
+       if (kvm_mips_map_page(kvm, gfn1) < 0)
                return -1;
 
-       pfn0 = kvm->arch.guest_pmap[
-               mips3_tlbpfn_to_paddr(tlb_lo[0]) >> PAGE_SHIFT];
-       pfn1 = kvm->arch.guest_pmap[
-               mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT];
+       pfn0 = kvm->arch.guest_pmap[gfn0];
+       pfn1 = kvm->arch.guest_pmap[gfn1];
 
        /* Get attributes from the Guest TLB */
        entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) |