[PATCH v18 14/15] vfio/type1: untag user pointers in vaddr_get_pfn

From: Andrey Konovalov
Date: Mon Jun 24 2019 - 10:33:59 EST

This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.

vaddr_get_pfn() uses provided user pointers for vma lookups, which can
only by done with untagged pointers.

Untag user pointers in this function.

Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
drivers/vfio/vfio_iommu_type1.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index add34adfadc7..7b8283e33d10 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -381,6 +381,8 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,


+ vaddr = untagged_addr(vaddr);
vma = find_vma_intersection(mm, vaddr, vaddr + 1);

if (vma && vma->vm_flags & VM_PFNMAP) {