File openssh-7.2p2-CVE-2018-15473.patch of Package openssh.21987

From 779974d35b4859c07bc3cb8a12c74b43b0a7d1e0 Mon Sep 17 00:00:00 2001
From: djm <djm@openbsd.org>
Date: Tue, 31 Jul 2018 03:10:27 +0000
Subject: [PATCH] =?UTF-8?q?delay=20bailout=20for=20invalid=20authenticatin?=
 =?UTF-8?q?g=20user=20until=20after=20the=20packet=20containing=20the=20re?=
 =?UTF-8?q?quest=20has=20been=20fully=20parsed.=20Reported=20by=20Dariusz?=
 =?UTF-8?q?=20Tytko=20and=20Micha=C5=82=20Sajdak;=20ok=20deraadt?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 usr.bin/ssh/auth2-gss.c       | 11 +++++++----
 usr.bin/ssh/auth2-hostbased.c | 11 ++++++-----
 usr.bin/ssh/auth2-pubkey.c    | 25 +++++++++++++++----------
 3 files changed, 28 insertions(+), 19 deletions(-)

Index: openssh-7.2p2/auth2-gss.c
===================================================================
--- openssh-7.2p2.orig/auth2-gss.c
+++ openssh-7.2p2/auth2-gss.c
@@ -102,9 +102,6 @@ userauth_gssapi(Authctxt *authctxt)
 	u_int len;
 	u_char *doid = NULL;
 
-	if (!authctxt->valid || authctxt->user == NULL)
-		return (0);
-
 	mechs = packet_get_int();
 	if (mechs == 0) {
 		debug("Mechanism negotiation is not supported");
@@ -135,6 +132,12 @@ userauth_gssapi(Authctxt *authctxt)
 		return (0);
 	}
 
+	if (!authctxt->valid || authctxt->user == NULL) {
+		debug2("userauth_hostbased: disabled because of invalid user");
+		free(doid);
+		return (0);
+	}
+
 	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
 		if (ctxt != NULL)
 			ssh_gssapi_delete_ctx(&ctxt);
Index: openssh-7.2p2/auth2-hostbased.c
===================================================================
--- openssh-7.2p2.orig/auth2-hostbased.c
+++ openssh-7.2p2/auth2-hostbased.c
@@ -66,10 +66,6 @@ userauth_hostbased(Authctxt *authctxt)
 	int pktype;
 	int authenticated = 0;
 
-	if (!authctxt->valid) {
-		debug2("userauth_hostbased: disabled because of invalid user");
-		return 0;
-	}
 	pkalg = packet_get_string(&alen);
 	pkblob = packet_get_string(&blen);
 	chost = packet_get_string(NULL);
@@ -114,6 +110,10 @@ userauth_hostbased(Authctxt *authctxt)
 		    __func__, sshkey_type(key));
 		goto done;
 	}
+	if (!authctxt->valid || authctxt->user == NULL) {
+		debug2("userauth_hostbased: disabled because of invalid user");
+		goto done;
+	}
 
 	service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
 	    authctxt->service;
Index: openssh-7.2p2/auth2-pubkey.c
===================================================================
--- openssh-7.2p2.orig/auth2-pubkey.c
+++ openssh-7.2p2/auth2-pubkey.c
@@ -79,16 +79,12 @@ userauth_pubkey(Authctxt *authctxt)
 {
 	Buffer b;
 	Key *key = NULL;
-	char *pkalg, *userstyle, *fp = NULL;
-	u_char *pkblob, *sig;
+	char *pkalg = NULL, *userstyle = NULL, *fp = NULL;
+	u_char *pkblob = NULL, *sig = NULL;
 	u_int alen, blen, slen;
 	int have_sig, pktype;
 	int authenticated = 0;
 
-	if (!authctxt->valid) {
-		debug2("%s: disabled because of invalid user", __func__);
-		return 0;
-	}
 	have_sig = packet_get_char();
 	if (datafellows & SSH_BUG_PKAUTH) {
 		debug2("%s: SSH_BUG_PKAUTH", __func__);
@@ -149,6 +145,10 @@ userauth_pubkey(Authctxt *authctxt)
 		} else {
 			buffer_put_string(&b, session_id2, session_id2_len);
 		}
+		if (!authctxt->valid || authctxt->user == NULL) {
+			debug2("userauth_hostbased: disabled because of invalid user");
+			goto done;
+		}
 		/* reconstruct packet */
 		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 		xasprintf(&userstyle, "%s%s%s", authctxt->user,
@@ -172,7 +173,6 @@ userauth_pubkey(Authctxt *authctxt)
 		buffer_dump(&b);
 #endif
 		pubkey_auth_info(authctxt, key, NULL);
-
 		/* test for correct signature */
 		authenticated = 0;
 		if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
@@ -184,12 +184,15 @@ userauth_pubkey(Authctxt *authctxt)
 			key = NULL; /* Don't free below */
 		}
 		buffer_free(&b);
-		free(sig);
 	} else {
 		debug("%s: test whether pkalg/pkblob are acceptable for %s %s",
 		    __func__, sshkey_type(key), fp);
 		packet_check_eom();
 
+		if (!authctxt->valid || authctxt->user == NULL) {
+			debug2("userauth_hostbased: disabled because of invalid user");
+			goto done;
+		}
 		/* XXX fake reply and always send PK_OK ? */
 		/*
 		 * XXX this allows testing whether a user is allowed
@@ -215,6 +219,7 @@ done:
 		key_free(key);
 	free(pkalg);
 	free(pkblob);
+	free(sig);
 	free(fp);
 	return authenticated;
 }