linux-kernel - [PATCH AUTOSEL for 4.14 103/110] xen/gntdev: Fix off-by-one error when unmapping with holes

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Message-ID: <20180203180015.29073-103-alexander.levin@microsoft.com>
Date:   Sat, 3 Feb 2018 18:01:32 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     Ross Lagerwall <ross.lagerwall@...rix.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 4.14 103/110] xen/gntdev: Fix off-by-one error
 when unmapping with holes

From: Ross Lagerwall <ross.lagerwall@...rix.com>

[ Upstream commit 951a010233625b77cde3430b4b8785a9a22968d1 ]

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>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.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 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);
-- 
2.11.0