Patch "MIPS: KVM: Add missing gfn range check" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

MIPS: KVM: Add missing gfn range check

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mips-kvm-add-missing-gfn-range-check.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: James Hogan <[email protected]>
Date: Thu, 11 Aug 2016 11:58:13 +0100
Subject: MIPS: KVM: Add missing gfn range check
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: James Hogan <[email protected]>

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.

---
 arch/mips/kvm/tlb.c |   23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

@@ -373,6 +373,7 @@ int kvm_mips_handle_mapped_seg_tlb_fault
 	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;
 

@@ -387,18 +388,24 @@ int kvm_mips_handle_mapped_seg_tlb_fault
 			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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/mips-kvm-add-missing-gfn-range-check.patch queue-4.7/mips-kvm-propagate-kseg0-mapped-tlb-fault-errors.patch queue-4.7/mips-kvm-fix-mapped-fault-broken-commpage-handling.patch queue-4.7/mips-kvm-fix-gfn-range-check-in-kseg0-tlb-faults.patch