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@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index f478a4c96d2f55cb2cf75abe50bfc2ce365c2a8e..419bdd4fc8b8ef062b8b39ba61f24c1911ce9ba4 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++;