On Wed, Sep 17, 2014 at 02:56:17PM -0700, Ard Biesheuvel wrote:
> Handle the potential NULL return value of find_vma_intersection()
> before dereferencing it.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
> arch/arm/kvm/mmu.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
> index 152e0f896e63..c093e95ff7ef 100644
> --- a/arch/arm/kvm/mmu.c
> +++ b/arch/arm/kvm/mmu.c
> @@ -776,7 +776,11 @@ 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(¤t->mm->mmap_sem);
> vma = find_vma_intersection(current->mm, hva, hva + 1);
> - if (is_vm_hugetlb_page(vma)) {
> + if (unlikely(!vma)) {
> + kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
> + up_read(¤t->mm->mmap_sem);
> + return -EFAULT;
> + } else if (is_vm_hugetlb_page(vma)) {
> hugetlb = true;
> gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT;
> } else {
> --
> 1.8.3.2
>
Nice catch!
(This would only happen if the guest unmaps an mmap region after
registering the memslot I believe, but still, we should absolutely merge
this.).
Thanks,
-Christoffer
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