Messages in this thread | | | Date | Fri, 26 Apr 2019 08:47:31 -0700 | From | Jacob Pan <> | Subject | Re: iommu/vt-d: drop mm use count if address is not canonical |
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On Fri, 26 Apr 2019 15:38:46 +0200 Joerg Roedel <joro@8bytes.org> wrote:
> [ Adding more people. ] > > On Wed, Apr 17, 2019 at 05:12:57PM +0800, Pan Bian wrote: > > The use count of svm->mm is incremented by mmget_not_zero. However, > > it is not dropped when the address is not canonical. This patch > > fixes the bug. > > > > Fixes: 9d8c3af31607("iommu/vt-d: IOMMU Page Request needs to check > > if address is canonical.") > > > > Signed-off-by: Pan Bian <bianpan2016@163.com> > > --- > > drivers/iommu/intel-svm.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c > > index 3a4b09a..2630d2e 100644 > > --- a/drivers/iommu/intel-svm.c > > +++ b/drivers/iommu/intel-svm.c > > @@ -574,8 +574,10 @@ static irqreturn_t prq_event_thread(int irq, > > void *d) goto bad_req; > > > > /* If address is not canonical, return invalid > > response */ > > - if (!is_canonical_address(address)) > > + if (!is_canonical_address(address)) { > > + mmput(svm->mm); > > goto bad_req; > > + } > > > > down_read(&svm->mm->mmap_sem); > > vma = find_extend_vma(svm->mm, address); > > I think it is better to move the canonical address check before > mmget_not_zero() like in the diff below. But I let David and Jacob > comment on this. > Looks good to me. Tested with PRQ and fake non canonical address then send an invalid page response.
Tested-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Regards, > > Joerg > > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c > index 8f87304f915c..5e9e1eee8336 100644 > --- a/drivers/iommu/intel-svm.c > +++ b/drivers/iommu/intel-svm.c > @@ -586,14 +586,15 @@ static irqreturn_t prq_event_thread(int irq, > void *d) > * any faults on kernel addresses. */ > if (!svm->mm) > goto bad_req; > - /* If the mm is already defunct, don't handle > faults. */ > - if (!mmget_not_zero(svm->mm)) > - goto bad_req; > > /* If address is not canonical, return invalid > response */ if (!is_canonical_address(address)) > goto bad_req; > > + /* If the mm is already defunct, don't handle > faults. */ > + if (!mmget_not_zero(svm->mm)) > + goto bad_req; > + > down_read(&svm->mm->mmap_sem); > vma = find_extend_vma(svm->mm, address); > if (!vma || address < vma->vm_start)
[Jacob Pan]
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