[PATCH 3.14 17/46] [PATCH BACKPORT 3.10-3.15 2/4] MIPS: KVM: Add missing gfn range check

Greg Kroah-Hartman
2016-08-18T13:54:39Z

commit 8985d50382359e5bf118fdbefc859d0dbf6cebc7 upstream.

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
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
[james.hogan@imgtec.com: Backport to v3.10.y - v3.15.y]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/mips/kvm/kvm_tlb.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

--- a/arch/mips/kvm/kvm_tlb.c
+++ b/arch/mips/kvm/kvm_tlb.c
@@ -370,6 +370,7 @@ kvm_mips_handle_mapped_seg_tlb_fault(str
unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
struct kvm *kvm = vcpu->kvm;
pfn_t pfn0, pfn1;
+ gfn_t gfn0, gfn1;
long tlb_lo[2];

tlb_lo[0] = tlb->tlb_lo0;
@@ -383,14 +384,24 @@ kvm_mips_handle_mapped_seg_tlb_fault(str
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, mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT) < 0)
+ if (kvm_mips_map_page(kvm, gfn0) < 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];
+ if (kvm_mips_map_page(kvm, gfn1) < 0)
+ return -1;
+
+ pfn0 = kvm->arch.guest_pmap[gfn0];
+ pfn1 = kvm->arch.guest_pmap[gfn1];

if (hpa0)
*hpa0 = pfn0 << PAGE_SHIFT;