lib/mpi: checks for zero divisor length

Divisor length should not be 0.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Reviewed-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

lib/mpi/mpi-div.c

diff --git a/lib/mpi/mpi-div.c b/lib/mpi/mpi-div.c
index c3087d1..8a45717 100644
--- a/lib/mpi/mpi-div.c
+++ b/lib/mpi/mpi-div.c
@@ -149,6 +149,9 @@
 	mpi_ptr_t marker[5];
 	int markidx = 0;
 
+	if (!dsize)
+		return -EINVAL;
+
 	memset(marker, 0, sizeof(marker));
 
 	/* Ensure space is enough for quotient and remainder.