[3.19.y-ckt stable] Patch "dm stats: fix divide by zero if 'number_of_areas' arg is zero" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

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

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.y-ckt4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 3f8371dcd4a41b801cfa9dc1551fbd8c8bdfb27f Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka at redhat.com>
Date: Fri, 5 Jun 2015 09:50:42 -0400
Subject: dm stats: fix divide by zero if 'number_of_areas' arg is zero

commit dd4c1b7d0c95be1c9245118a3accc41a16f1db67 upstream.

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 at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/md/dm-stats.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index f478a4c..419bdd4 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++;
--
1.9.1