krb5: Fix CVE-2023-36054

lib/kadm5/kadm_rpc_xdr.c in MIT Kerberos 5 (aka krb5) before 1.20.2
and 1.21.x before 1.21.1 frees an uninitialized pointer. A remote
authenticated user can trigger a kadmind crash. This occurs because
_xdr_kadm5_principal_ent_rec does not validate the relationship
between n_key_data and the key_data array count.

References:
https://nvd.nist.gov/vuln/detail/CVE-2023-36054

Signed-off-by: Soumya Sambu <soumya.sambu@windriver.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

2 files changed, 69 insertions, 0 deletions

diff --git a/meta-oe/recipes-connectivity/krb5/krb5/CVE-2023-36054.patch b/meta-oe/recipes-connectivity/krb5/krb5/CVE-2023-36054.patch
new file mode 100644
index 000000000..160c090bc
--- /dev/null
+++ b/meta-oe/recipes-connectivity/krb5/krb5/CVE-2023-36054.patch
@@ -0,0 +1,68 @@
+From ef08b09c9459551aabbe7924fb176f1583053cdd Mon Sep 17 00:00:00 2001
+From: Greg Hudson <ghudson@mit.edu>
+Date: Mon, 21 Aug 2023 03:08:15 +0000
+Subject: [PATCH] Ensure array count consistency in kadm5 RPC
+
+In _xdr_kadm5_principal_ent_rec(), ensure that n_key_data matches the
+key_data array count when decoding.  Otherwise when the structure is
+later freed, xdr_array() could iterate over the wrong number of
+elements, either leaking some memory or freeing uninitialized
+pointers.  Reported by Robert Morris.
+
+CVE: CVE-2023-36054
+
+An authenticated attacker can cause a kadmind process to crash by
+freeing uninitialized pointers.  Remote code execution is unlikely.
+An attacker with control of a kadmin server can cause a kadmin client
+to crash by freeing uninitialized pointers.
+
+ticket: 9099 (new)
+tags: pullup
+target_version: 1.21-next
+target_version: 1.20-next
+
+Upstream-Status: Backport [https://github.com/krb5/krb5/commit/ef08b09c9459551aabbe7924fb176f1583053cdd]
+
+Signed-off-by: Soumya Sambu <soumya.sambu@windriver.com>
+---
+ src/lib/kadm5/kadm_rpc_xdr.c | 11 ++++++++---
+ 1 file changed, 8 insertions(+), 3 deletions(-)
+
+diff --git a/src/lib/kadm5/kadm_rpc_xdr.c b/src/lib/kadm5/kadm_rpc_xdr.c
+index 2892d41..94b1ce8 100644
+--- a/src/lib/kadm5/kadm_rpc_xdr.c
++++ b/src/lib/kadm5/kadm_rpc_xdr.c
+@@ -390,6 +390,7 @@ _xdr_kadm5_principal_ent_rec(XDR *xdrs, kadm5_principal_ent_rec *objp,
+                             int v)
+ {
+        unsigned int n;
++       bool_t r;
+
+        if (!xdr_krb5_principal(xdrs, &objp->principal)) {
+                return (FALSE);
+@@ -443,6 +444,9 @@ _xdr_kadm5_principal_ent_rec(XDR *xdrs, kadm5_principal_ent_rec *objp,
+        if (!xdr_krb5_int16(xdrs, &objp->n_key_data)) {
+                return (FALSE);
+        }
++       if (xdrs->x_op == XDR_DECODE && objp->n_key_data < 0) {
++               return (FALSE);
++       }
+        if (!xdr_krb5_int16(xdrs, &objp->n_tl_data)) {
+                return (FALSE);
+        }
+@@ -451,9 +455,10 @@ _xdr_kadm5_principal_ent_rec(XDR *xdrs, kadm5_principal_ent_rec *objp,
+                return FALSE;
+        }
+        n = objp->n_key_data;
+-       if (!xdr_array(xdrs, (caddr_t *) &objp->key_data,
+-                      &n, ~0, sizeof(krb5_key_data),
+-                      xdr_krb5_key_data_nocontents)) {
++       r = xdr_array(xdrs, (caddr_t *) &objp->key_data, &n, objp->n_key_data,
++                     sizeof(krb5_key_data), xdr_krb5_key_data_nocontents);
++       objp->n_key_data = n;
++       if (!r) {
+                return (FALSE);
+        }
+
+--
+2.40.0
diff --git a/meta-oe/recipes-connectivity/krb5/krb5_1.20.1.bb b/meta-oe/recipes-connectivity/krb5/krb5_1.20.1.bb
index 10fff11c2..e353b58aa 100644
--- a/meta-oe/recipes-connectivity/krb5/krb5_1.20.1.bb
+++ b/meta-oe/recipes-connectivity/krb5/krb5_1.20.1.bb
@@ -29,6 +29,7 @@ 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-2023-36054.patch;striplevel=2 \
 "
 SRC_URI[md5sum] = "73f5780e7b587ccd8b8cfc10c965a686"
 SRC_URI[sha256sum] = "704aed49b19eb5a7178b34b2873620ec299db08752d6a8574f95d41879ab8851"