rpms/krb5
7
0
Fork 0
Code Issues Pull Requests Releases Activity

Fix KDC null deref on TGS inner body null server (CVE-2021-37750)

Browse Source
This commit is contained in:
Robbie Harwood 2021-08-19 12:29:56 -04:00
parent 03e8c69837
commit ca196a9d6b
2 changed files with 50 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch Normal file
View File

@ -0,0 +1,45 @@
From bb8fa495d00ccd931eec87a01b8920636cf7903e Mon Sep 17 00:00:00 2001
From: Greg Hudson <ghudson@mit.edu>
Date: Tue, 3 Aug 2021 01:15:27 -0400
Subject: [PATCH] Fix KDC null deref on TGS inner body null server
After the KDC decodes a FAST inner body, it does not check for a null
server. Prior to commit 39548a5b17bbda9eeb63625a201cfd19b9de1c5b this
would typically result in an error from krb5_unparse_name(), but with
the addition of get_local_tgt() it results in a null dereference. Add
a null check.
Reported by Joseph Sutton of Catalyst.
CVE-2021-37750:
In MIT krb5 releases 1.14 and later, an authenticated attacker can
cause a null dereference in the KDC by sending a FAST TGS request with
no server field.
ticket: 9008 (new)
tags: pullup
target_version: 1.19-next
target_version: 1.18-next
(cherry picked from commit d775c95af7606a51bf79547a94fa52ddd1cb7f49)
---
src/kdc/do_tgs_req.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/src/kdc/do_tgs_req.c b/src/kdc/do_tgs_req.c
index 6d244ffd4..39a504ca1 100644
--- a/src/kdc/do_tgs_req.c
+++ b/src/kdc/do_tgs_req.c
@@ -207,6 +207,11 @@ process_tgs_req(krb5_kdc_req *request, krb5_data *pkt,
status = "FIND_FAST";
goto cleanup;
}
+ if (sprinc == NULL) {
+ status = "NULL_SERVER";
+ errcode = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN;
+ goto cleanup;
+ }
errcode = get_local_tgt(kdc_context, &sprinc->realm, header_server,
&local_tgt, &local_tgt_storage, &local_tgt_key);

6
krb5.spec
View File

@ -42,7 +42,7 @@
Summary: The Kerberos network authentication system
Name: krb5
Version: 1.19.2
Release: %{?zdpd}1%{?dist}
Release: %{?zdpd}2%{?dist}
# rharwood has trust path to signing key and verifies on check-in
Source0: https://web.mit.edu/kerberos/dist/krb5/%{version}/krb5-%{version}%{?dashpre}.tar.gz
@ -89,6 +89,7 @@ Patch24: Fix-leaks-on-error-in-kadm5-init-functions.patch
Patch25: Clean-up-context-after-failed-open-in-libkdb5.patch
Patch26: Use-asan-in-one-of-the-CI-builds.patch
Patch29: Clean-up-gssapi_krb5-ccache-name-functions.patch
Patch30: Fix-KDC-null-deref-on-TGS-inner-body-null-server.patch
License: MIT
URL: https://web.mit.edu/kerberos/www/
@ -651,6 +652,9 @@ exit 0
%{_libdir}/libkadm5srv_mit.so.*
%changelog
* Thu Aug 19 2021 Robbie Harwood <rharwood@redhat.com> - 1.19.2-2
- Fix KDC null deref on TGS inner body null server (CVE-2021-37750)
* Mon Jul 26 2021 Robbie Harwood <rharwood@redhat.com> - 1.19.2-1
- New upstream version (1.19.2)