1 files changed, 1 insertions, 0 deletions

diff --git a/src/lib/libcrypto/bn/bn_gf2m.c b/src/lib/libcrypto/bn/bn_gf2m.c
index 527b0fa15b..432a3aa338 100644
--- a/src/lib/libcrypto/bn/bn_gf2m.c
+++ b/src/lib/libcrypto/bn/bn_gf2m.c
@@ -545,6 +545,7 @@ int BN_GF2m_mod_inv(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
                 {
                 while (!BN_is_odd(u))
                         {
+                        if (BN_is_zero(u)) goto err;
                         if (!BN_rshift1(u, u)) goto err;
                         if (BN_is_odd(b))
                                 {