Fix faulty check of padding in x_long.c

[openssl.git] / crypto / asn1 / x_long.c

diff --git a/crypto/asn1/x_long.c b/crypto/asn1/x_long.c
index f804282c51b29ebb4c0c3275f0971aea0eb3f793..a7b90231c0e6f790158cd0e807779630ee8e340e 100644 (file)
--- a/crypto/asn1/x_long.c
+++ b/crypto/asn1/x_long.c
@@ -1,59 +1,10 @@
 /*
- * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL project
- * 2000.
- */
-/* ====================================================================
- * Copyright (c) 2000 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
- *    licensing@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).
+ * Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
  *
+ * Licensed under the OpenSSL license (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>
@@ -125,7 +76,7 @@ static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
      * set.
      */
     if (ltmp < 0)
-        utmp = -ltmp - 1;
+        utmp = 0 - (unsigned long)ltmp - 1;
     else
         utmp = ltmp;
     clen = BN_num_bits_word(utmp);
@@ -154,19 +105,44 @@ static int long_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
 static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
                     int utype, char *free_cont, const ASN1_ITEM *it)
 {
-    int neg, i;
+    int neg = -1, i;
     long ltmp;
     unsigned long utmp = 0;
     char *cp = (char *)pval;
+
+    if (len > 1) {
+        /*
+         * Check possible pad byte.  Worst case, we're skipping past actual
+         * content, but since that's only with 0x00 and 0xff and we set neg
+         * accordingly, the result will be correct in the end anyway.
+         */
+        switch (cont[0]) {
+        case 0xff:
+            cont++;
+            len--;
+            neg = 0x80;
+            break;
+        case 0:
+            cont++;
+            len--;
+            neg = 0;
+            break;
+        }
+    }
     if (len > (int)sizeof(long)) {
         ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
         return 0;
     }
-    /* Is it negative? */
-    if (len && (cont[0] & 0x80))
-        neg = 1;
-    else
-        neg = 0;
+    if (neg == -1) {
+        /* Is it negative? */
+        if (len && (cont[0] & 0x80))
+            neg = 1;
+        else
+            neg = 0;
+    } else if (neg == (cont[0] & 0x80)) {
+        ASN1err(ASN1_F_LONG_C2I, ASN1_R_ILLEGAL_PADDING);
+        return 0;
+    }
     utmp = 0;
     for (i = 0; i < len; i++) {
         utmp <<= 8;
@@ -176,9 +152,13 @@ static int long_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
             utmp |= cont[i];
     }
     ltmp = (long)utmp;
+    if (ltmp < 0) {
+        ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);
+        return 0;
+    }
     if (neg) {
-        ltmp++;
         ltmp = -ltmp;
+        ltmp--;
     }
     if (ltmp == it->size) {
         ASN1err(ASN1_F_LONG_C2I, ASN1_R_INTEGER_TOO_LARGE_FOR_LONG);