File openssl-CVE-2015-0293.patch of Package openssl.6981

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File openssl-CVE-2015-0293.patch of Package openssl.6981

commit a40c1bcb8c37fbad24d8f28f0fb0204d76f0fee2
Author: Emilia Kasper <emilia@openssl.org>
Date:   Wed Mar 4 09:05:02 2015 -0800

Fix reachable assert in SSLv2 servers.
    
    This assert is reachable for servers that support SSLv2 and export ciphers.
    Therefore, such servers can be DoSed by sending a specially crafted
    SSLv2 CLIENT-MASTER-KEY.
    
    Also fix s2_srvr.c to error out early if the key lengths are malformed.
    These lengths are sent unencrypted, so this does not introduce an oracle.
    
    CVE-2015-0293
    
    This issue was discovered by Sean Burford (Google) and Emilia Käsper of
    the OpenSSL development team.
    
    Reviewed-by: Richard Levitte <levitte@openssl.org>
    Reviewed-by: Tim Hudson <tjh@openssl.org>

Index: openssl-1.0.1i/ssl/s2_lib.c
===================================================================
--- openssl-1.0.1i.orig/ssl/s2_lib.c	2015-03-17 14:05:13.745459798 +0100
+++ openssl-1.0.1i/ssl/s2_lib.c	2015-03-17 14:05:14.763474757 +0100
@@ -487,7 +487,7 @@ int ssl2_generate_key_material(SSL *s)
 
 		OPENSSL_assert(s->session->master_key_length >= 0
 		    && s->session->master_key_length
-		    < (int)sizeof(s->session->master_key));
+		    <= (int)sizeof(s->session->master_key));
 		EVP_DigestUpdate(&ctx,s->session->master_key,s->session->master_key_length);
 		EVP_DigestUpdate(&ctx,&c,1);
 		c++;
Index: openssl-1.0.1i/ssl/s2_srvr.c
===================================================================
--- openssl-1.0.1i.orig/ssl/s2_srvr.c	2015-03-17 14:05:13.721459445 +0100
+++ openssl-1.0.1i/ssl/s2_srvr.c	2015-03-17 14:07:43.262655766 +0100
@@ -446,9 +446,6 @@ static int get_client_master_key(SSL *s)
 		SSLerr(SSL_F_GET_CLIENT_MASTER_KEY,SSL_R_NO_PRIVATEKEY);
 		return(-1);
 		}
-	i=ssl_rsa_private_decrypt(s->cert,s->s2->tmp.enc,
-		&(p[s->s2->tmp.clear]),&(p[s->s2->tmp.clear]),
-		(s->s2->ssl2_rollback)?RSA_SSLV23_PADDING:RSA_PKCS1_PADDING);
 
 	is_export=SSL_C_IS_EXPORT(s->session->cipher);
 	
@@ -467,21 +464,59 @@ static int get_client_master_key(SSL *s)
 	else
 		ek=5;
 
+    /*
+     * The format of the CLIENT-MASTER-KEY message is
+     * 1 byte message type
+     * 3 bytes cipher
+     * 2-byte clear key length (stored in s->s2->tmp.clear)
+     * 2-byte encrypted key length (stored in s->s2->tmp.enc)
+     * 2-byte key args length (IV etc)
+     * clear key
+     * encrypted key
+     * key args
+     *
+     * If the cipher is an export cipher, then the encrypted key bytes
+     * are a fixed portion of the total key (5 or 8 bytes). The size of
+     * this portion is in |ek|. If the cipher is not an export cipher,
+     * then the entire key material is encrypted (i.e., clear key length
+     * must be zero).
+     */
+    if ((!is_export && s->s2->tmp.clear != 0) ||
+        (is_export && s->s2->tmp.clear + ek != EVP_CIPHER_key_length(c))) {
+        ssl2_return_error(s, SSL2_PE_UNDEFINED_ERROR);
+        SSLerr(SSL_F_GET_CLIENT_MASTER_KEY,SSL_R_BAD_LENGTH);
+        return -1;
+    }
+    /*
+     * The encrypted blob must decrypt to the encrypted portion of the key.
+     * Decryption can't be expanding, so if we don't have enough encrypted
+     * bytes to fit the key in the buffer, stop now.
+     */
+    if ((is_export && s->s2->tmp.enc < ek) ||
+        (!is_export && s->s2->tmp.enc < EVP_CIPHER_key_length(c))) {
+        ssl2_return_error(s,SSL2_PE_UNDEFINED_ERROR);
+        SSLerr(SSL_F_GET_CLIENT_MASTER_KEY,SSL_R_LENGTH_TOO_SHORT);
+        return -1;
+    }
+
+    i = ssl_rsa_private_decrypt(s->cert, s->s2->tmp.enc,
+                                &(p[s->s2->tmp.clear]),
+                                &(p[s->s2->tmp.clear]),
+                                (s->s2->ssl2_rollback) ? RSA_SSLV23_PADDING :
+                                RSA_PKCS1_PADDING);
+
 	/* bad decrypt */
 #if 1
 	/* If a bad decrypt, continue with protocol but with a
 	 * random master secret (Bleichenbacher attack) */
-	if ((i < 0) ||
-		((!is_export && (i != EVP_CIPHER_key_length(c)))
-		|| (is_export && ((i != ek) || (s->s2->tmp.clear+(unsigned int)i !=
-			(unsigned int)EVP_CIPHER_key_length(c))))))
-		{
+    if ((i < 0) || ((!is_export && i != EVP_CIPHER_key_length(c))
+                    || (is_export && i != ek))) {
 		ERR_clear_error();
 		if (is_export)
 			i=ek;
 		else
 			i=EVP_CIPHER_key_length(c);
-		if (RAND_pseudo_bytes(p,i) <= 0)
+	        if (RAND_pseudo_bytes(&p[s->s2->tmp.clear], i) <= 0)
 			return 0;
 		}
 #else
@@ -505,7 +540,8 @@ static int get_client_master_key(SSL *s)
 		}
 #endif
 
-	if (is_export) i+=s->s2->tmp.clear;
+	if (is_export)
+	        i = EVP_CIPHER_key_length(c);
 
 	if (i > SSL_MAX_MASTER_KEY_LENGTH)
 		{

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