Bug#1091820: corrected patch

Oops, sorry; the patch I included earlier was reversed. :/ Here's the correct version.

-- 
   Richard

diff --git a/kex.c b/kex.c
index db6717e9..6f06a4f7 100644
--- a/kex.c
+++ b/kex.c
@@ -378,14 +378,25 @@ kex_proposal_populate_entries(struct ssh *ssh, char *prop[PROPOSAL_MAX],
  	const char *defpropclient[PROPOSAL_MAX] = { KEX_CLIENT };
  	const char **defprop = ssh->kex->server ? defpropserver : defpropclient;
  	u_int i;
-	char *cp;
+	char *cp, *hkalgs_prop;

  	if (prop == NULL)
  		fatal_f("proposal missing");

-	/* Append EXT_INFO signalling to KexAlgorithms */
+	/* our hostkey algorithm proposal */
+	hkalgs_prop = xstrdup(hkalgs ? hkalgs : defprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
+
+	/*
+	 * If we don't have a hostkey (sshd_config "HostKey none" =>
+	 * hkalgs_prop list is empty), there's no point in including
+	 * the default kex algorithms; start with the empty list
+	 * instead. GSSAPI code will later add the dynamically
+	 * determined gss-* algorithms.
+	 */
  	if (kexalgos == NULL)
-		kexalgos = defprop[PROPOSAL_KEX_ALGS];
+		kexalgos = strlen(hkalgs_prop) == 0 ? "" : defprop[PROPOSAL_KEX_ALGS];
+
+	/* Append feature signalling to KexAlgorithms. */
  	if ((cp = kex_names_cat(kexalgos, ssh->kex->server ?
  	    "ext-info-s,[email protected]" :
  	    "ext-info-c,[email protected]")) == NULL)
@@ -409,7 +420,7 @@ kex_proposal_populate_entries(struct ssh *ssh, char *prop[PROPOSAL_MAX],
  			prop[i] = xstrdup(comp ? comp : defprop[i]);
  			break;
  		case PROPOSAL_SERVER_HOST_KEY_ALGS:
-			prop[i] = xstrdup(hkalgs ? hkalgs : defprop[i]);
+			prop[i] = hkalgs_prop;
  			break;
  		default:
  			prop[i] = xstrdup(defprop[i]);
diff --git a/sshd.c b/sshd.c
index 6dfa5fff..625c1f32 100644
--- a/sshd.c
+++ b/sshd.c
@@ -2505,14 +2505,6 @@ do_ssh2_kex(struct ssh *ssh)
  	char *newstr = NULL;
  	orig = myproposal[PROPOSAL_KEX_ALGS];

-	/*
-	 * If we don't have a host key, then there's no point advertising
-	 * the other key exchange algorithms
-	 */
-
-	if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
-		orig = NULL;
-
  	if (options.gss_keyex)
  		gss = ssh_gssapi_server_mechanisms();
  	else
@@ -2531,7 +2523,7 @@ do_ssh2_kex(struct ssh *ssh)
  	 * host key algorithm we support
  	 */
  	if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0)
-		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = "null";
+		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = xstrdup("null");

  	if (newstr)
  		myproposal[PROPOSAL_KEX_ALGS] = newstr;