The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 07956b6269d3ed05d854233d5bb776dca91751dd Mon Sep 17 00:00:00 2001
From: Alex Williamson alex.williamson@redhat.com Date: Tue, 16 Feb 2021 15:49:34 -0700 Subject: [PATCH] vfio/type1: Use follow_pte()
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()") Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Cornelia Huck cohuck@redhat.com Reviewed-by: Peter Xu peterx@redhat.com Signed-off-by: Alex Williamson alex.williamson@redhat.com
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index b3df383d7028..ed03f3fcb07e 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -24,6 +24,7 @@ #include <linux/compat.h> #include <linux/device.h> #include <linux/fs.h> +#include <linux/highmem.h> #include <linux/iommu.h> #include <linux/module.h> #include <linux/mm.h> @@ -462,9 +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, &ptep, &ptl); if (ret) { bool unlocked = false;
@@ -478,9 +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, &ptep, &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; }