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authorJason Gunthorpe <jgg@mellanox.com>2018-06-29 11:31:50 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-07-11 16:31:26 +0200
commit5cdc9e29ffb074a4062100825d4d049e202818a7 (patch)
tree35147e989b683d30ab0d2a88e029acdcc9dfc87c
parenta3be6357ded22c64ba4836cd744d8b2038c8edc4 (diff)
vfio: Use get_user_pages_longterm correctly
commit bb94b55af3461e26b32f0e23d455abeae0cfca5d upstream. The patch noted in the fixes below converted get_user_pages_fast() to get_user_pages_longterm(), however the two calls differ in a few ways. First _fast() is documented to not require the mmap_sem, while _longterm() is documented to need it. Hold the mmap sem as required. Second, _fast accepts an 'int write' while _longterm uses 'unsigned int gup_flags', so the expression '!!(prot & IOMMU_WRITE)' is only working by luck as FOLL_WRITE is currently == 0x1. Use the expected FOLL_WRITE constant instead. Fixes: 94db151dc892 ("vfio: disable filesystem-dax page pinning") Cc: <stable@vger.kernel.org> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Acked-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/vfio/vfio_iommu_type1.c16
1 files changed, 7 insertions, 9 deletions
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 3c082451ab1a..0586ad5eb590 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -346,18 +346,16 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
struct page *page[1];
struct vm_area_struct *vma;
struct vm_area_struct *vmas[1];
+ unsigned int flags = 0;
int ret;
+ if (prot & IOMMU_WRITE)
+ flags |= FOLL_WRITE;
+
+ down_read(&mm->mmap_sem);
if (mm == current->mm) {
- ret = get_user_pages_longterm(vaddr, 1, !!(prot & IOMMU_WRITE),
- page, vmas);
+ ret = get_user_pages_longterm(vaddr, 1, flags, page, vmas);
} else {
- unsigned int flags = 0;
-
- if (prot & IOMMU_WRITE)
- flags |= FOLL_WRITE;
-
- down_read(&mm->mmap_sem);
ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,
vmas, NULL);
/*
@@ -371,8 +369,8 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
ret = -EOPNOTSUPP;
put_page(page[0]);
}
- up_read(&mm->mmap_sem);
}
+ up_read(&mm->mmap_sem);
if (ret == 1) {
*pfn = page_to_pfn(page[0]);