[ 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 <bianpan2...@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. 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) _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu