PR: 2540

Submitted by: emmanuel.azencot@bull.net
Reviewed by: steve

Prevent infinite loop in BN_GF2m_mod_inv().

diff --git a/crypto/bn/bn_gf2m.c b/crypto/bn/bn_gf2m.c
index 527b0fa15be51ada3725d3d77704b26e8f8619ff..432a3aa3383a35f5360e7a4ca09402c0806019da 100644 (file)
--- a/crypto/bn/bn_gf2m.c
+++ b/crypto/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))
                                {