xen/gntdev: avoid out of bounds access in case of partial gntdev_mmap()

commit 298d275d4d upstream.

In case gntdev_mmap() succeeds only partially in mapping grant pages
it will leave some vital information uninitialized needed later for
cleanup. This will lead to an out of bounds array access when unmapping
the already mapped pages.

So just initialize the data needed for unmapping the pages a little bit
earlier.

Reported-by: Arthur Borsboom <arthurborsboom@gmail.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Juergen Gross
2017-10-25 17:08:07 +02:00
committed by Greg Kroah-Hartman
parent 8783885ea7
commit d431d9f122

View File

@@ -1030,6 +1030,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
mutex_unlock(&priv->lock);
if (use_ptemod) {
map->pages_vm_start = vma->vm_start;
err = apply_to_page_range(vma->vm_mm, vma->vm_start,
vma->vm_end - vma->vm_start,
find_grant_ptes, map);
@@ -1067,7 +1068,6 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
set_grant_ptes_as_special, NULL);
}
#endif
map->pages_vm_start = vma->vm_start;
}
return 0;