Fix bug found by Tim Prouty, logging off and then re-using a vuid can cause smbd to

access a freed structure.
Jeremy.

diff --git a/source/smbd/uid.c b/source/smbd/uid.c
index 02f8cc950e9ce24872512301913d3904c0a31022..bec820b719920f5c38343a3379c4c9928158b654 100644 (file)
--- a/source/smbd/uid.c
+++ b/source/smbd/uid.c
@@ -166,6 +166,10 @@ void conn_clear_vuid_cache(connection_struct *conn, uint16_t vuid)
 
                if (ent->vuid == vuid) {
                        ent->vuid = UID_FIELD_INVALID;
+                       /* Ensure we're not freeing an active pointer. */
+                       if (conn->server_info == ent->server_info) {
+                               conn->server_info = NULL;
+                       }
                        TALLOC_FREE(ent->server_info);
                        ent->read_only = False;
                        ent->admin_user = False;
@@ -218,6 +222,13 @@ bool change_to_user(connection_struct *conn, uint16 vuid)
 
        server_info = vuser ? vuser->server_info : conn->server_info;
 
+       if (!server_info) {
+               /* Invalid vuid sent - even with security = share. */
+               DEBUG(2,("change_to_user: Invalid vuid %d used on "
+                        "share %s.\n",vuid, lp_servicename(snum) ));
+               return false;
+       }
+
        if (!check_user_ok(conn, vuid, server_info, snum)) {
                DEBUG(2,("change_to_user: SMB user %s (unix user %s, vuid %d) "
                         "not permitted access to share %s.\n",