From 0a5575f3f6db134589423075fa5a37a1e1353306 Mon Sep 17 00:00:00 2001
From: Andy Polyakov <appro@openssl.org>
Date: Fri, 30 Mar 2012 17:40:52 +0000
Subject: [PATCH] bn/bn_gf2m.c: make new BN_GF2m_mod_inv work with
 BN_DEBUG_RAND [from HEAD].

---
 crypto/bn/bn_gf2m.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/crypto/bn/bn_gf2m.c b/crypto/bn/bn_gf2m.c
index 08ab9fd227..8a4dc20ad9 100644
--- a/crypto/bn/bn_gf2m.c
+++ b/crypto/bn/bn_gf2m.c
@@ -628,8 +628,11 @@ int BN_GF2m_mod_inv(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
 			}
 		if (ubits==vbits)
 			{
-			bn_correct_top(u);
-			ubits = BN_num_bits(u);
+			BN_ULONG ul;
+			int utop = (ubits-1)/BN_BITS2;
+
+			while ((ul=udp[utop])==0 && utop) utop--;
+			ubits = utop*BN_BITS2 + BN_num_bits_word(ul);
 			}
 		}
 	bn_correct_top(b);
-- 
2.25.1