deps: cherry-pick eca441b2 from OpenSSL

Original commit message:

    bn_exp.c: fix x86_64-specific crash with one-word modulus.

    PR: #3397

Signed-off-by: Fedor Indutny <[email protected]>

deps/openssl/openssl/crypto/bn/bn_exp.c

@@ -680,7 +680,7 @@ int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
 
     /* Dedicated window==4 case improves 512-bit RSA sign by ~15%, but as
      * 512-bit RSA is hardly relevant, we omit it to spare size... */ 
-    if (window==5)
+    if (window==5 && top>1)
 	{
 	void bn_mul_mont_gather5(BN_ULONG *rp,const BN_ULONG *ap,
 			const void *table,const BN_ULONG *np,

test/simple/test-crypto-dh-odd-key.js

@@ -0,0 +1,31 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+
+var crypto = require('crypto');
+var odd = new Buffer(39);
+odd.fill('A');
+
+var c = crypto.createDiffieHellman(32);
+c.setPrivateKey(odd);
+c.generateKeys();