From: Tom Yu <tlyu@mit.edu>
Date: Tue, 6 Dec 2011 20:42:46 +0000 (+0000)
Subject: SA-2011-007 KDC null pointer deref in TGS handling [CVE-2011-1530]
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=8d6a83d1163fafb8e9308313c83ce0472864abbb;p=krb5.git

SA-2011-007 KDC null pointer deref in TGS handling [CVE-2011-1530]

Fix a null pointer dereference condition that could cause a denial of
service.

ticket: 7042
target_version: 1.10
tags: pullup

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@25525 dc483132-0cff-0310-8789-dd5450dbe970
---

diff --git a/src/kdc/Makefile.in b/src/kdc/Makefile.in
index 118f8f780..8994a6a76 100644
--- a/src/kdc/Makefile.in
+++ b/src/kdc/Makefile.in
@@ -71,6 +71,7 @@ check-unix:: rtest
 
 check-pytests::
 	$(RUNPYTEST) $(srcdir)/t_workers.py $(PYTESTFLAGS)
+	$(RUNPYTEST) $(srcdir)/t_emptytgt.py $(PYTESTFLAGS)
 
 install::
 	$(INSTALL_PROGRAM) krb5kdc ${DESTDIR}$(SERVER_BINDIR)/krb5kdc
diff --git a/src/kdc/do_tgs_req.c b/src/kdc/do_tgs_req.c
index 0f001d67c..56d9869c1 100644
--- a/src/kdc/do_tgs_req.c
+++ b/src/kdc/do_tgs_req.c
@@ -238,7 +238,8 @@ tgt_again:
                     if (!tgs_1 || !data_eq(*server_1, *tgs_1)) {
                         errcode = find_alternate_tgs(request, &server);
                         firstpass = 0;
-                        goto tgt_again;
+                        if (errcode == 0)
+                            goto tgt_again;
                     }
                 }
                 status = "UNKNOWN_SERVER";
diff --git a/src/kdc/t_emptytgt.py b/src/kdc/t_emptytgt.py
new file mode 100644
index 000000000..1760bcd5a
--- /dev/null
+++ b/src/kdc/t_emptytgt.py
@@ -0,0 +1,8 @@
+#!/usr/bin/python
+from k5test import *
+
+realm = K5Realm(start_kadmind=False, create_host=False)
+output = realm.run_as_client([kvno, 'krbtgt/'], expected_code=1)
+if 'not found in Kerberos database' not in output:
+    fail('TGT lookup for empty realm failed in unexpected way')
+success('Empty tgt lookup.')