From: Mikulas Patocka <mpatocka@redhat.com>
Date: Fri, 5 Jun 2015 13:50:42 +0000 (-0400)
Subject: dm stats: fix divide by zero if 'number_of_areas' arg is zero
X-Git-Tag: v3.18.18~54
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=83891b4cab7ee6cecc1050c533826f9b27c03270;p=thirdparty%2Fkernel%2Fstable.git

dm stats: fix divide by zero if 'number_of_areas' arg is zero

[ Upstream commit dd4c1b7d0c95be1c9245118a3accc41a16f1db67 ]

If the number_of_areas argument was zero the kernel would crash on
div-by-zero.  Add better input validation.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # v3.12+
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 87f86c77b0940..6f2a4ce413f7b 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -795,6 +795,8 @@ static int message_stats_create(struct mapped_device *md,
 		return -EINVAL;
 
 	if (sscanf(argv[2], "/%u%c", &divisor, &dummy) == 1) {
+		if (!divisor)
+			return -EINVAL;
 		step = end - start;
 		if (do_div(step, divisor))
 			step++;