commit 37b544087ef3f65ca68465ba39291a07195dac26
author Ard Biesheuvel <ard.biesheuvel@linaro.org> Wed Sep 17 14:56:17 2014 -0700
committer Christoffer Dall <christoffer.dall@linaro.org> Fri Oct 10 13:07:37 2014 +0200
tree e6fcb2b1fa3bdca8ca899c7bc515d4848a909296
parent e9e8578b6cdfba0259e99e79f0cb80c55c99b3c2

arm/arm64: KVM: fix potential NULL dereference in user_mem_abort()

Handle the potential NULL return value of find_vma_intersection()
before dereferencing it.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm/kvm/mmu.c

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 8f0c7a4..bb2e110 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -776,6 +776,12 @@
 	/* 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 (unlikely(!vma)) {
+		kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
+		up_read(&current->mm->mmap_sem);
+		return -EFAULT;
+	}
+
 	if (is_vm_hugetlb_page(vma)) {
 		hugetlb = true;
 		gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;