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 87f86c77b0940256aff09a4e26de8805d52b9dde..6f2a4ce413f7bc8319a82d183c4648ff7f5b61eb 100644 (file)
--- 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++;