From 69087d69d01a4530e2d588036fcbeaf8856b2ff1 Mon Sep 17 00:00:00 2001 From: Yi Zhao Date: Mon, 6 Sep 2021 14:32:53 +0800 Subject: krb5: fix CVE-2021-36222 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 Signed-off-by: Khem Raj --- .../krb5/krb5/CVE-2021-36222.patch | 121 +++++++++++++++++++++ meta-oe/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 (limited to 'meta-oe') 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 0000000000..fee6e64c15 --- /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 +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 +--- + 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 6c4b4575ee..197c1e096b 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" -- cgit 1.2.3-korg