[PATCH 3.14 23/34] arm/arm64: KVM: fix potential NULL dereference in user_mem_abort()

[Greg Kroah-Hartman]

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheu...@linaro.org>

commit 37b544087ef3f65ca68465ba39291a07195dac26 upstream.

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

Acked-by: Marc Zyngier <marc.zyng...@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.d...@linaro.org>
Signed-off-by: Shannon Zhao <shannon.z...@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/arm/kvm/mmu.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -778,6 +778,12 @@ static int user_mem_abort(struct kvm_vcp
        /* 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;


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