Avoid potential overflow to the sign bit when shifting left 24 places

[openssl.git] / crypto / bn / bn_mpi.c

diff --git a/crypto/bn/bn_mpi.c b/crypto/bn/bn_mpi.c
index 86d96750b9c7ce66698c4d9f9bb71ccd6c3cb18d..d2be44e2bdbe4e6a5848785d6843d1f4bbd0a802 100644 (file)
--- a/crypto/bn/bn_mpi.c
+++ b/crypto/bn/bn_mpi.c
@@ -1,63 +1,15 @@
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
+/*
+ * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
  *
- * This package is an SSL implementation written
- * by Eric Young (eay@cryptsoft.com).
- * The implementation was written so as to conform with Netscapes SSL.
- *
- * This library is free for commercial and non-commercial use as long as
- * the following conditions are aheared to.  The following conditions
- * apply to all code found in this distribution, be it the RC4, RSA,
- * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
- * included with this distribution is covered by the same copyright terms
- * except that the holder is Tim Hudson (tjh@cryptsoft.com).
- *
- * Copyright remains Eric Young's, and as such any Copyright notices in
- * the code are not to be removed.
- * If this package is used in a product, Eric Young should be given attribution
- * as the author of the parts of the library used.
- * This can be in the form of a textual message at program startup or
- * in documentation (online or textual) provided with the package.
- *
- * 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 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 acknowledgement:
- *    "This product includes cryptographic software written by
- *     Eric Young (eay@cryptsoft.com)"
- *    The word 'cryptographic' can be left out if the rouines from the library
- *    being used are not cryptographic related :-).
- * 4. If you include any Windows specific code (or a derivative thereof) from
- *    the apps directory (application code) you must include an acknowledgement:
- *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
- *
- * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
- * ANY EXPRESS 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 AUTHOR OR 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.
- *
- * The licence and distribution terms for any publically available version or
- * derivative of this code cannot be changed.  i.e. this code cannot simply be
- * copied and put under another distribution licence
- * [including the GNU Public Licence.]
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
  */
 
 #include <stdio.h>
 #include "internal/cryptlib.h"
-#include "bn_lcl.h"
+#include "bn_local.h"
 
 int BN_bn2mpi(const BIGNUM *a, unsigned char *d)
 {
@@ -87,12 +39,13 @@ int BN_bn2mpi(const BIGNUM *a, unsigned char *d)
     return (num + 4 + ext);
 }
 
-BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *a)
+BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *ain)
 {
     long len;
     int neg = 0;
+    BIGNUM *a = NULL;
 
-    if (n < 4) {
+    if (n < 4 || (d[0] & 0x80) != 0) {
         BNerr(BN_F_BN_MPI2BN, BN_R_INVALID_LENGTH);
         return NULL;
     }
@@ -103,8 +56,11 @@ BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *a)
         return NULL;
     }
 
-    if (a == NULL)
+    if (ain == NULL)
         a = BN_new();
+    else
+        a = ain;
+
     if (a == NULL)
         return NULL;
 
@@ -117,7 +73,8 @@ BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *a)
     if ((*d) & 0x80)
         neg = 1;
     if (BN_bin2bn(d, (int)len, a) == NULL) {
-        BN_free(a);
+        if (ain == NULL)
+            BN_free(a);
         return NULL;
     }
     a->neg = neg;