|
 |
27013b |
From 0a8dfc380fe3b210662ba1b1d452fcec2f84841b Mon Sep 17 00:00:00 2001
|
|
|
f4b6e2 |
From: Greg Hudson <ghudson@mit.edu>
|
|
|
f4b6e2 |
Date: Tue, 3 Aug 2021 01:15:27 -0400
|
|
|
f4b6e2 |
Subject: [PATCH] Fix KDC null deref on TGS inner body null server
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
After the KDC decodes a FAST inner body, it does not check for a null
|
|
|
f4b6e2 |
server. Prior to commit 39548a5b17bbda9eeb63625a201cfd19b9de1c5b this
|
|
|
f4b6e2 |
would typically result in an error from krb5_unparse_name(), but with
|
|
|
f4b6e2 |
the addition of get_local_tgt() it results in a null dereference. Add
|
|
|
f4b6e2 |
a null check.
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
Reported by Joseph Sutton of Catalyst.
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
CVE-2021-37750:
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
In MIT krb5 releases 1.14 and later, an authenticated attacker can
|
|
|
f4b6e2 |
cause a null dereference in the KDC by sending a FAST TGS request with
|
|
|
f4b6e2 |
no server field.
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
ticket: 9008 (new)
|
|
|
f4b6e2 |
tags: pullup
|
|
|
f4b6e2 |
target_version: 1.19-next
|
|
|
f4b6e2 |
target_version: 1.18-next
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
(cherry picked from commit d775c95af7606a51bf79547a94fa52ddd1cb7f49)
|
|
|
f4b6e2 |
(cherry picked from commit bb8fa495d00ccd931eec87a01b8920636cf7903e)
|
|
|
f4b6e2 |
(cherry picked from commit dfe383f8251d0edc7e5e08ec5e4fdd9b7f902b2a)
|
|
|
f4b6e2 |
---
|
|
|
f4b6e2 |
src/kdc/do_tgs_req.c | 5 +++++
|
|
|
f4b6e2 |
1 file changed, 5 insertions(+)
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
diff --git a/src/kdc/do_tgs_req.c b/src/kdc/do_tgs_req.c
|
|
|
f4b6e2 |
index 463a9c0dd..7c596a111 100644
|
|
|
f4b6e2 |
--- a/src/kdc/do_tgs_req.c
|
|
|
f4b6e2 |
+++ b/src/kdc/do_tgs_req.c
|
|
|
f4b6e2 |
@@ -208,6 +208,11 @@ process_tgs_req(krb5_kdc_req *request, krb5_data *pkt,
|
|
|
f4b6e2 |
status = "FIND_FAST";
|
|
|
f4b6e2 |
goto cleanup;
|
|
|
f4b6e2 |
}
|
|
|
f4b6e2 |
+ if (sprinc == NULL) {
|
|
|
f4b6e2 |
+ status = "NULL_SERVER";
|
|
|
f4b6e2 |
+ errcode = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN;
|
|
|
f4b6e2 |
+ goto cleanup;
|
|
|
f4b6e2 |
+ }
|
|
|
f4b6e2 |
|
|
|
f4b6e2 |
errcode = get_local_tgt(kdc_context, &sprinc->realm, header_server,
|
|
|
f4b6e2 |
&local_tgt, &local_tgt_storage, &local_tgt_key);
|