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Subject[PATCH] vfio/type1: Use follow_pte()
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Date
follow_pfn() doesn't make sure that we're using the correct page
protections, get the pte with follow_pte() so that we can test
protections and get the pfn from the pte.

Fixes: 5cbf3264bc71 ("vfio/type1: Fix VA->PA translation for PFNMAP VMAs in vaddr_get_pfn()")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index ec9fd95a138b..90715413c3d9 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -463,9 +463,11 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
unsigned long vaddr, unsigned long *pfn,
bool write_fault)
{
+ pte_t *ptep;
+ spinlock_t *ptl;
int ret;

- ret = follow_pfn(vma, vaddr, pfn);
+ ret = follow_pte(vma->vm_mm, vaddr, NULL, &ptep, NULL, &ptl);
if (ret) {
bool unlocked = false;

@@ -479,9 +481,17 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
if (ret)
return ret;

- ret = follow_pfn(vma, vaddr, pfn);
+ ret = follow_pte(vma->vm_mm, vaddr, NULL, &ptep, NULL, &ptl);
+ if (ret)
+ return ret;
}

+ if (write_fault && !pte_write(*ptep))
+ ret = -EFAULT;
+ else
+ *pfn = pte_pfn(*ptep);
+
+ pte_unmap_unlock(ptep, ptl);
return ret;
}

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