linux-kernel - [PATCH 1/2] xen/gntdev: Fix off-by-one error when unmapping with holes

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Date:   Tue, 9 Jan 2018 12:10:21 +0000
From:   Ross Lagerwall <ross.lagerwall@...rix.com>
To:     <xen-devel@...ts.xenproject.org>
CC:     Ross Lagerwall <ross.lagerwall@...rix.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] 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@...rix.com>
---
 drivers/xen/gntdev.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 57efbd3..d3391a1 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);
-- 
2.9.5