From 3142b0bdfcb12ec46569f62d48780982a2c26f47 Mon Sep 17 00:00:00 2001
From: Steffen Jaeckel <s@jaeckel.eu>
Date: Mon, 13 Oct 2014 16:51:13 +0200
Subject: [PATCH] fp_prime_random_ex: make sure call-back function is not NULL

---
 src/numtheory/fp_prime_random_ex.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/numtheory/fp_prime_random_ex.c b/src/numtheory/fp_prime_random_ex.c
index 3debce3..b9dd68e 100644
--- a/src/numtheory/fp_prime_random_ex.c
+++ b/src/numtheory/fp_prime_random_ex.c
@@ -16,7 +16,7 @@ int fp_prime_random_ex(fp_int *a, int t, int size, int flags, tfm_prime_callback
    int res, err, bsize, maskOR_msb_offset;
 
    /* sanity check the input */
-   if (size <= 1 || t <= 0 || t > FP_PRIME_SIZE) {
+   if (size <= 1 || cb == NULL || t <= 0 || t > FP_PRIME_SIZE) {
       return FP_VAL;
    }