From: Rich Salz <rsalz@openssl.org>
Date: Mon, 6 Mar 2017 14:54:17 +0000 (-0500)
Subject: Fix an endless loop in rsa_builtin_keygen.
X-Git-Tag: OpenSSL_1_1_1-pre1~2106
X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=697958313ba48c8ebc832ab8f9f2b845fb7acfd4

Fix an endless loop in rsa_builtin_keygen.

And add a test case.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2757)
---

diff --git a/crypto/rsa/rsa_gen.c b/crypto/rsa/rsa_gen.c
index 0d1d56bfe7..4ced965519 100644
--- a/crypto/rsa/rsa_gen.c
+++ b/crypto/rsa/rsa_gen.c
@@ -43,6 +43,16 @@ static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
     int bitsp, bitsq, ok = -1, n = 0;
     BN_CTX *ctx = NULL;
 
+    /*
+     * When generating ridiculously small keys, we can get stuck
+     * continually regenerating the same prime values.
+     */
+    if (bits < 16) {
+        ok = 0;             /* we set our own err */
+        RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
+        goto err;
+    }
+
     ctx = BN_CTX_new();
     if (ctx == NULL)
         goto err;
@@ -94,21 +104,10 @@ static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
     if (!BN_GENCB_call(cb, 3, 0))
         goto err;
     for (;;) {
-        /*
-         * When generating ridiculously small keys, we can get stuck
-         * continually regenerating the same prime values. Check for this and
-         * bail if it happens 3 times.
-         */
-        unsigned int degenerate = 0;
         do {
             if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
                 goto err;
-        } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
-        if (degenerate == 3) {
-            ok = 0;             /* we set our own err */
-            RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
-            goto err;
-        }
+        } while (BN_cmp(rsa->p, rsa->q) == 0);
         if (!BN_sub(r2, rsa->q, BN_value_one()))
             goto err;
         if (!BN_gcd(r1, r2, rsa->e, ctx))
diff --git a/test/recipes/15-test_genrsa.t b/test/recipes/15-test_genrsa.t
new file mode 100644
index 0000000000..cc74e303f1
--- /dev/null
+++ b/test/recipes/15-test_genrsa.t
@@ -0,0 +1,26 @@
+#! /usr/bin/env perl
+# Copyright 2017 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
+
+
+use strict;
+use warnings;
+
+use File::Spec;
+use OpenSSL::Test qw/:DEFAULT srctop_file/;
+use OpenSSL::Test::Utils;
+
+setup("test_genrsa");
+
+plan tests => 5;
+
+is(run(app([ 'openssl', 'genrsa', '-3', '-out', 'genrsatest.pem', '8'])), 0, "genrsa -3 8");
+ok(run(app([ 'openssl', 'genrsa', '-3', '-out', 'genrsatest.pem', '16'])), "genrsa -3 16");
+ok(run(app([ 'openssl', 'rsa', '-check', '-in', 'genrsatest.pem', '-noout'])), "rsa -check");
+ok(run(app([ 'openssl', 'genrsa', '-f4', '-out', 'genrsatest.pem', '16'])), "genrsa -f4 16");
+ok(run(app([ 'openssl', 'rsa', '-check', '-in', 'genrsatest.pem', '-noout'])), "rsa -check");
+unlink 'genrsatest.pem';