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

Greg Kroah-Hartman
2015-07-01T18:42:19Z

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

commit 37b544087ef3f65ca68465ba39291a07195dac26 upstream.

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>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@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;