Reject excessively large primes in DH key generation.

CVE-2018-0732 Signed-off-by: Guido Vranken <guidovranken@gmail.com> (cherry picked from commit 91f7361) Reviewed-by: Tim Hudson <tjh@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from #6457)
openssl · Jun 12, 2018 · ea7abee · ea7abee
1 parent 9a236d5
commit ea7abee
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/crypto/dh/dh_key.c b/crypto/dh/dh_key.c
@@ -78,10 +78,15 @@ 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;