From 10028bd326e47f731a5887586dae4d097e5a6f8e Mon Sep 17 00:00:00 2001
From: Nikos Mavrogiannopoulos <nmav@redhat.com>
Date: Mon, 2 Jan 2017 13:44:46 +0100
Subject: wrap_nettle_mpi_modm: bail on a modulus that is zero

Relates #156
---
 lib/nettle/mpi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/nettle/mpi.c b/lib/nettle/mpi.c
index 61fddfb7e0..c8dccf6e64 100644
--- a/lib/nettle/mpi.c
+++ b/lib/nettle/mpi.c
@@ -233,6 +233,9 @@ static void wrap_nettle_mpi_clear(bigint_t a)
 
 static int wrap_nettle_mpi_modm(bigint_t r, const bigint_t a, const bigint_t b)
 {
+	if (mpz_cmp_ui(TOMPZ(b), 0) == 0)
+		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
+
 	mpz_mod(TOMPZ(r), TOMPZ(a), TOMPZ(b));
 	
 	return 0;
-- 
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