From: Ross Lagerwall <ross.lagerwall@citrix.com>
Date: Tue, 9 Jan 2018 12:10:21 +0000 (+0000)
Subject: xen/gntdev: Fix off-by-one error when unmapping with holes
X-Git-Tag: v4.15-rc8~15^2~1
X-Git-Url: http://git.agner.ch/gitweb/?a=commitdiff_plain;h=951a010233625b77cde3430b4b8785a9a22968d1;p=linux.git

xen/gntdev: Fix off-by-one error when unmapping with holes

If the requested range has a hole, the calculation of the number of
pages to unmap is off by one. Fix it.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 57efbd3b053b..d3391a1e3796 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -380,10 +380,8 @@ static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 		}
 		range = 0;
 		while (range < pages) {
-			if (map->unmap_ops[offset+range].handle == -1) {
-				range--;
+			if (map->unmap_ops[offset+range].handle == -1)
 				break;
-			}
 			range++;
 		}
 		err = __unmap_grant_pages(map, offset, range);