From: Guido Vranken <guidovranken@gmail.com>
Date: Mon, 11 Jun 2018 17:38:54 +0000 (+0200)
Subject: Reject excessively large primes in DH key generation.
X-Git-Tag: OpenSSL_1_0_2p~40
X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff_plain;h=3984ef0b72831da8b3ece4745cac4f8575b19098;ds=sidebyside

Reject excessively large primes in DH key generation.

CVE-2018-0732

Signed-off-by: Guido Vranken <guidovranken@gmail.com>

(cherry picked from commit 91f7361f47b082ae61ffe1a7b17bb2adf213c7fe)

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6457)
---

diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
index 387558f146..f235e0d682 100644
--- a/crypto/dh/dh_key.c
+++ b/crypto/dh/dh_key.c
@@ -130,10 +130,15 @@ static int generate_key(DH *dh)
     int ok = 0;
     int generate_new_key = 0;
     unsigned l;
-    BN_CTX *ctx;
+    BN_CTX *ctx = NULL;
     BN_MONT_CTX *mont = NULL;
     BIGNUM *pub_key = NULL, *priv_key = NULL;
 
+    if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
+        DHerr(DH_F_GENERATE_KEY, DH_R_MODULUS_TOO_LARGE);
+        return 0;
+    }
+
     ctx = BN_CTX_new();
     if (ctx == NULL)
         goto err;