nsswitch: fix crash on null pam change pw response

The function _pam_winbind_change_pwd crashes due to a null value passed
to the function strcasecmp and denies to login via graphical login
manager. Check for a null value before doing a strcasecmp.

Bug-Ubuntu: https://bugs.launchpad.net/bugs/1003296
Bug: https://bugzilla.samba.org/show_bug.cgi?id=9013

Autobuild-User(master): David Disseldorp <ddiss@samba.org>
Autobuild-Date(master): Wed Sep 12 00:07:28 CEST 2012 on sn-devel-104

diff --git a/nsswitch/pam_winbind.c b/nsswitch/pam_winbind.c
index e3e9af19a3220691d431b6078cc1da033d60ba52..fb84985155ef7e7ca1853677d7b9b21bc3a043ec 100644 (file)
--- a/nsswitch/pam_winbind.c
+++ b/nsswitch/pam_winbind.c
@@ -831,7 +831,7 @@ static bool _pam_winbind_change_pwd(struct pwb_context *ctx)
        }
        _pam_log(ctx, LOG_CRIT, "Received [%s] reply from application.\n", resp->resp);
 
-       if (strcasecmp(resp->resp, "yes") == 0) {
+       if ((resp->resp != NULL) && (strcasecmp(resp->resp, "yes") == 0)) {
                retval = true;
        }