From mboxrd@z Thu Jan  1 00:00:00 1970
From: marc.zyngier@arm.com (Marc Zyngier)
Date: Thu, 09 Oct 2014 14:13:16 +0100
Subject: [PATCH 2/6] arm/arm64: KVM: fix potential NULL dereference in
 user_mem_abort()
In-Reply-To: <20141009131146.GY3717@cbox>
References: <1410990981-665-1-git-send-email-ard.biesheuvel@linaro.org>
 <1410990981-665-3-git-send-email-ard.biesheuvel@linaro.org>
 <543687FD.2020504@arm.com>
 <CAKv+Gu91GFy=K=_oe6iSF9jG0_VwOw3T8=vX0S4vN8Ah4=s8MQ@mail.gmail.com>
 <20141009131146.GY3717@cbox>
Message-ID: <543689EC.9030106@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 09/10/14 14:11, Christoffer Dall wrote:
> On Thu, Oct 09, 2014 at 03:10:08PM +0200, Ard Biesheuvel wrote:
>> On 9 October 2014 15:05, Marc Zyngier <marc.zyngier@arm.com> wrote:
>>> On 17/09/14 22:56, Ard Biesheuvel wrote:
>>>> Handle the potential NULL return value of find_vma_intersection()
>>>> before dereferencing it.
>>>>
>>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>> ---
>>>>  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(&current->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(&current->mm->mmap_sem);
>>>> +             return -EFAULT;
>>>> +     } else if (is_vm_hugetlb_page(vma)) {
>>>
>>> I'm not overly fond of this "else if" construct. The !vma case is final,
>>> so what's after cannot be reached.
>>>
>>
>> I don't have a strong preference either way. I can respin but perhaps
>> Christoffer can fix it up when applying?
>>
> Sure!  Don't respin these just for that.

In which case, please add my

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

when you do the fixup.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...