From mboxrd@z Thu Jan 1 00:00:00 1970 From: christoffer.dall@linaro.org (Christoffer Dall) Date: Thu, 9 Oct 2014 15:11:46 +0200 Subject: [PATCH 2/6] arm/arm64: KVM: fix potential NULL dereference in user_mem_abort() In-Reply-To: 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> Message-ID: <20141009131146.GY3717@cbox> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Oct 09, 2014 at 03:10:08PM +0200, Ard Biesheuvel wrote: > On 9 October 2014 15:05, Marc Zyngier 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 > >> --- > >> 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)) { > > > > 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. -Christoffer