From ef08b09c9459551aabbe7924fb176f1583053cdd Mon Sep 17 00:00:00 2001 From: Greg Hudson Date: Wed, 21 Jun 2023 10:57:39 -0400 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-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 --- 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 0411c3fd3f4..287cae750f9 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); }