[RESEND PATCH v4 8/9] xen/gntdev.c: Convert to use vm_map_pages()

[Souptick Joarder]

Convert to use vm_map_pages() to map range of kernel
memory to user vma.

map->count is passed to vm_map_pages() and internal API
verify map->count against count ( count = vma_pages(vma))
for page array boundary overrun condition.

Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 drivers/xen/gntdev.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 5efc5ee..5d64262 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1084,7 +1084,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 	int index = vma->vm_pgoff;
 	int count = vma_pages(vma);
 	struct gntdev_grant_map *map;
-	int i, err = -EINVAL;
+	int err = -EINVAL;
 
 	if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 		return -EINVAL;
@@ -1145,12 +1145,9 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 		goto out_put_map;
 
 	if (!use_ptemod) {
-		for (i = 0; i < count; i++) {
-			err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
-				map->pages[i]);
-			if (err)
-				goto out_put_map;
-		}
+		err = vm_map_pages(vma, map->pages, map->count);
+		if (err)
+			goto out_put_map;
 	} else {
 #ifdef CONFIG_X86
 		/*
-- 
1.9.1