From 675f605d44630d491f10c846344679e8fc90b119 Mon Sep 17 00:00:00 2001
From: Bodo Möller <bodo@openssl.org>
Date: Wed, 14 Jun 2006 08:55:23 +0000
Subject: Thread-safety fixes

---
 crypto/bn/bn_mont.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 75 insertions(+), 10 deletions(-)

(limited to 'crypto/bn/bn_mont.c')

diff --git a/crypto/bn/bn_mont.c b/crypto/bn/bn_mont.c
index c2cfecf370..b532305b80 100644
--- a/crypto/bn/bn_mont.c
+++ b/crypto/bn/bn_mont.c
@@ -55,6 +55,59 @@
  * copied and put under another distribution licence
  * [including the GNU Public Licence.]
  */
+/* ====================================================================
+ * Copyright (c) 1998-2006 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    openssl-core@openssl.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ *
+ */
 
 /*
  * Details about Montgomery multiplication algorithms can be found at
@@ -427,18 +480,30 @@ BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)
 BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock,
 					const BIGNUM *mod, BN_CTX *ctx)
 	{
-	if (*pmont)
-		return *pmont;
-	CRYPTO_w_lock(lock);
+	int got_write_lock = 0;
+
+	CRYPTO_r_lock(lock);
 	if (!*pmont)
 		{
-		BN_MONT_CTX *mtmp;
-		mtmp = BN_MONT_CTX_new();
-		if (mtmp && !BN_MONT_CTX_set(mtmp, mod, ctx))
-			BN_MONT_CTX_free(mtmp);
-		else
-			*pmont = mtmp;
+		CRYPTO_r_unlock(lock);
+		CRYPTO_w_lock(lock);
+		got_write_lock = 1;
+
+		if (!*pmont)
+			{
+			BN_MONT_CTX *mtmp;
+			mtmp = BN_MONT_CTX_new();
+			if (mtmp && !BN_MONT_CTX_set(mtmp, mod, ctx))
+				BN_MONT_CTX_free(mtmp);
+			else
+				*pmont = mtmp;
+			}
 		}
-	CRYPTO_w_unlock(lock);
+	
+	if (got_write_lock)
+		CRYPTO_w_unlock(lock);
+	else
+		CRYPTO_r_unlock(lock);
+		
 	return *pmont;
 	}
-- 
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