* [meta-oe][PATCH] krb5: fix CVE-2021-36222
@ 2021-09-06 6:32 Yi Zhao
0 siblings, 0 replies; only message in thread
From: Yi Zhao @ 2021-09-06 6:32 UTC (permalink / raw)
To: openembedded-devel
CVE-2021-36222:
ec_verify in kdc/kdc_preauth_ec.c in the Key Distribution Center (KDC)
in MIT Kerberos 5 (aka krb5) before 1.18.4 and 1.19.x before 1.19.2
allows remote attackers to cause a NULL pointer dereference and daemon
crash. This occurs because a return value is not properly managed in a
certain situation.
References:
https://nvd.nist.gov/vuln/detail/CVE-2021-36222
Patches from:
https://github.com/krb5/krb5/commit/fc98f520caefff2e5ee9a0026fdf5109944b3562
Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
---
.../krb5/krb5/CVE-2021-36222.patch | 121 ++++++++++++++++++
.../recipes-connectivity/krb5/krb5_1.17.2.bb | 1 +
2 files changed, 122 insertions(+)
create mode 100644 meta-oe/recipes-connectivity/krb5/krb5/CVE-2021-36222.patch
diff --git a/meta-oe/recipes-connectivity/krb5/krb5/CVE-2021-36222.patch b/meta-oe/recipes-connectivity/krb5/krb5/CVE-2021-36222.patch
new file mode 100644
index 000000000..fee6e64c1
--- /dev/null
+++ b/meta-oe/recipes-connectivity/krb5/krb5/CVE-2021-36222.patch
@@ -0,0 +1,121 @@
+From fc98f520caefff2e5ee9a0026fdf5109944b3562 Mon Sep 17 00:00:00 2001
+From: Joseph Sutton <josephsutton@catalyst.net.nz>
+Date: Wed, 7 Jul 2021 11:47:44 +1200
+Subject: [PATCH] Fix KDC null deref on bad encrypted challenge
+
+The function ec_verify() in src/kdc/kdc_preauth_ec.c contains a check
+to avoid further processing if the armor key is NULL. However, this
+check is bypassed by a call to k5memdup0() which overwrites retval
+with 0 if the allocation succeeds. If the armor key is NULL, a call
+to krb5_c_fx_cf2_simple() will then dereference it, resulting in a
+crash. Add a check before the k5memdup0() call to avoid overwriting
+retval.
+
+CVE-2021-36222:
+
+In MIT krb5 releases 1.16 and later, an unauthenticated attacker can
+cause a null dereference in the KDC by sending a request containing a
+PA-ENCRYPTED-CHALLENGE padata element without using FAST.
+
+[ghudson@mit.edu: trimmed patch; added test case; edited commit
+message]
+
+ticket: 9007 (new)
+tags: pullup
+target_version: 1.19-next
+target_version: 1.18-next
+
+CVE: CVE-2021-36222
+
+Upstream-Status: Backport
+[https://github.com/krb5/krb5/commit/fc98f520caefff2e5ee9a0026fdf5109944b3562]
+
+Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
+---
+ src/kdc/kdc_preauth_ec.c | 3 ++-
+ src/tests/Makefile.in | 1 +
+ src/tests/t_cve-2021-36222.py | 46 +++++++++++++++++++++++++++++++++++
+ 3 files changed, 49 insertions(+), 1 deletion(-)
+ create mode 100644 src/tests/t_cve-2021-36222.py
+
+diff --git a/src/kdc/kdc_preauth_ec.c b/src/kdc/kdc_preauth_ec.c
+index 7e636b3f9..43a9902cc 100644
+--- a/src/kdc/kdc_preauth_ec.c
++++ b/src/kdc/kdc_preauth_ec.c
+@@ -87,7 +87,8 @@ ec_verify(krb5_context context, krb5_data *req_pkt, krb5_kdc_req *request,
+ }
+
+ /* Check for a configured FAST ec auth indicator. */
+- realmstr = k5memdup0(realm.data, realm.length, &retval);
++ if (retval == 0)
++ realmstr = k5memdup0(realm.data, realm.length, &retval);
+ if (realmstr != NULL)
+ retval = profile_get_string(context->profile, KRB5_CONF_REALMS,
+ realmstr,
+diff --git a/src/tests/Makefile.in b/src/tests/Makefile.in
+index fc6fcc0c3..1a1938306 100644
+--- a/src/tests/Makefile.in
++++ b/src/tests/Makefile.in
+@@ -166,6 +166,7 @@ check-pytests: unlockiter s4u2self
+ $(RUNPYTEST) $(srcdir)/t_cve-2012-1015.py $(PYTESTFLAGS)
+ $(RUNPYTEST) $(srcdir)/t_cve-2013-1416.py $(PYTESTFLAGS)
+ $(RUNPYTEST) $(srcdir)/t_cve-2013-1417.py $(PYTESTFLAGS)
++ $(RUNPYTEST) $(srcdir)/t_cve-2021-36222.py $(PYTESTFLAGS)
+ $(RM) au.log
+ $(RUNPYTEST) $(srcdir)/t_audit.py $(PYTESTFLAGS)
+ $(RUNPYTEST) $(srcdir)/jsonwalker.py -d $(srcdir)/au_dict.json \
+diff --git a/src/tests/t_cve-2021-36222.py b/src/tests/t_cve-2021-36222.py
+new file mode 100644
+index 000000000..57e04993b
+--- /dev/null
++++ b/src/tests/t_cve-2021-36222.py
+@@ -0,0 +1,46 @@
++import socket
++from k5test import *
++
++realm = K5Realm()
++
++# CVE-2021-36222 KDC null dereference on encrypted challenge preauth
++# without FAST
++
++s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
++a = (hostname, realm.portbase)
++
++m = ('6A81A0' '30819D' # [APPLICATION 10] SEQUENCE
++ 'A103' '0201' '05' # [1] pvno = 5
++ 'A203' '0201' '0A' # [2] msg-type = 10
++ 'A30E' '300C' # [3] padata = SEQUENCE OF
++ '300A' # SEQUENCE
++ 'A104' '0202' '008A' # [1] padata-type = PA-ENCRYPTED-CHALLENGE
++ 'A202' '0400' # [2] padata-value = ""
++ 'A48180' '307E' # [4] req-body = SEQUENCE
++ 'A007' '0305' '0000000000' # [0] kdc-options = 0
++ 'A120' '301E' # [1] cname = SEQUENCE
++ 'A003' '0201' '01' # [0] name-type = NT-PRINCIPAL
++ 'A117' '3015' # [1] name-string = SEQUENCE-OF
++ '1B06' '6B7262746774' # krbtgt
++ '1B0B' '4B5242544553542E434F4D'
++ # KRBTEST.COM
++ 'A20D' '1B0B' '4B5242544553542E434F4D'
++ # [2] realm = KRBTEST.COM
++ 'A320' '301E' # [3] sname = SEQUENCE
++ 'A003' '0201' '01' # [0] name-type = NT-PRINCIPAL
++ 'A117' '3015' # [1] name-string = SEQUENCE-OF
++ '1B06' '6B7262746774' # krbtgt
++ '1B0B' '4B5242544553542E434F4D'
++ # KRBTEST.COM
++ 'A511' '180F' '31393934303631303036303331375A'
++ # [5] till = 19940610060317Z
++ 'A703' '0201' '00' # [7] nonce = 0
++ 'A808' '3006' # [8] etype = SEQUENCE OF
++ '020112' '020111') # aes256-cts aes128-cts
++
++s.sendto(bytes.fromhex(m), a)
++
++# Make sure kinit still works.
++realm.kinit(realm.user_princ, password('user'))
++
++success('CVE-2021-36222 regression test')
+--
+2.25.1
+
diff --git a/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb b/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb
index 6c4b4575e..197c1e096 100644
--- a/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb
+++ b/meta-oe/recipes-connectivity/krb5/krb5_1.17.2.bb
@@ -30,6 +30,7 @@ SRC_URI = "http://web.mit.edu/kerberos/dist/${BPN}/${SHRT_VER}/${BP}.tar.gz \
file://etc/default/krb5-admin-server \
file://krb5-kdc.service \
file://krb5-admin-server.service \
+ file://CVE-2021-36222.patch;striplevel=2 \
"
SRC_URI[md5sum] = "aa4337fffa3b61f22dbd0167f708818f"
SRC_URI[sha256sum] = "1a4bba94df92f6d39a197a10687653e8bfbc9a2076e129f6eb92766974f86134"
--
2.25.1
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