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

From: Souptick Joarder
Date: Mon Mar 18 2019 - 22:25:35 EST


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