[PATCH 1/2] ARM: KVM: fix NULL pointer dereference when VMA not found

[Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>]

If the user tries to access an invalid memory region, a NULL pointer
dereference may happen inside the kernel. Handle this more gracefully.

Signed-off-by: Nikolay Nikolaev <n.nikolaev@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Antonios Motakis <a.motakis@xxxxxxxxxxxxxxxxxxxxxx>
---
 arch/arm/kvm/mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 7789857..7466e56 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -662,7 +662,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	/* Let's check if we will get back a huge page backed by hugetlbfs */
 	down_read(&current->mm->mmap_sem);
 	vma = find_vma_intersection(current->mm, hva, hva + 1);
-	if (is_vm_hugetlb_page(vma)) {
+	if (likely(vma) && is_vm_hugetlb_page(vma)) {
 		hugetlb = true;
 		gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
 	} else {
-- 
1.8.3.2

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