You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
47 lines
1.6 KiB
47 lines
1.6 KiB
From 0a8dfc380fe3b210662ba1b1d452fcec2f84841b 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) |
|
(cherry picked from commit bb8fa495d00ccd931eec87a01b8920636cf7903e) |
|
(cherry picked from commit dfe383f8251d0edc7e5e08ec5e4fdd9b7f902b2a) |
|
--- |
|
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 463a9c0dd..7c596a111 100644 |
|
--- a/src/kdc/do_tgs_req.c |
|
+++ b/src/kdc/do_tgs_req.c |
|
@@ -208,6 +208,11 @@ 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);
|
|
|