| Message ID | 1410990981-665-3-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
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@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(¤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
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(¤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. > hugetlb = true; > gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT; > } else { > Despite the above nit: Acked-by: Marc Zyngier <marc.zyngier@arm.com> M.
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(¤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? >> hugetlb = true; >> gfn = (fault_ipa & PMD_MASK) >> PAGE_SHIFT; >> } else { >> > > Despite the above nit: > > Acked-by: Marc Zyngier <marc.zyngier@arm.com> > Thanks.
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(¤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
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(¤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. In which case, please add my Acked-by: Marc Zyngier <marc.zyngier@arm.com> when you do the fixup. Thanks, M.
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 {
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(-)