krb5 commit [krb5-1.19]: Fix uncommon PKINIT memory leak

[ghudson at mit.edu]

https://github.com/krb5/krb5/commit/441736872285e6538e6b6c78eab60862d3b6dcaa
commit 441736872285e6538e6b6c78eab60862d3b6dcaa
Author: sashan <anedvedicky at gmail.com>
Date:   Sun May 29 10:32:57 2022 +0200

    Fix uncommon PKINIT memory leak
    
    PKINIT per-request module data objects are normally created by
    pkinit_server_verify_padata() and freed by
    pkinit_server_return_padata().  In some unusual circumstances, the KDC
    may not call the return_padata method after verification succeeds.
    Add a free_modreq method and free the object there instead.
    
    [ghudson at mit.edu: rewrote commit message]
    
    (cherry picked from commit 883415036a4b4e0372b84a5a6e46c10b3a67aba0)
    
    ticket: 9065
    version_fixed: 1.19.4

 src/plugins/preauth/pkinit/pkinit_srv.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/plugins/preauth/pkinit/pkinit_srv.c b/src/plugins/preauth/pkinit/pkinit_srv.c
index 3ae56c064..26fccccae 100644
--- a/src/plugins/preauth/pkinit/pkinit_srv.c
+++ b/src/plugins/preauth/pkinit/pkinit_srv.c
@@ -1026,7 +1026,6 @@ pkinit_server_return_padata(krb5_context context,
     (*send_pa)->contents = (krb5_octet *) out_data->data;
 
 cleanup:
-    pkinit_fini_kdc_req_context(context, reqctx);
     free(scratch.data);
     free(out_data);
     if (encoded_dhkey_info != NULL)
@@ -1615,6 +1614,13 @@ pkinit_fini_kdc_req_context(krb5_context context, void *ctx)
     free(reqctx);
 }
 
+static void
+pkinit_free_modreq(krb5_context context, krb5_kdcpreauth_moddata moddata,
+                   krb5_kdcpreauth_modreq modreq)
+{
+    pkinit_fini_kdc_req_context(context, modreq);
+}
+
 krb5_error_code
 kdcpreauth_pkinit_initvt(krb5_context context, int maj_ver, int min_ver,
                          krb5_plugin_vtable vtable);
@@ -1636,5 +1642,6 @@ kdcpreauth_pkinit_initvt(krb5_context context, int maj_ver, int min_ver,
     vt->edata = pkinit_server_get_edata;
     vt->verify = pkinit_server_verify_padata;
     vt->return_padata = pkinit_server_return_padata;
+    vt->free_modreq = pkinit_free_modreq;
     return 0;
 }