commit 2cbf596225aa96b9b5785eb3d772e0fb66f0ba01
Author: Ira Cooper <ira@samba.org>
Date:   Wed May 23 21:39:03 2012 -0400

    s3-passdb: Fix negative SID->uid/gid cache handling.
    
    -1 uid/gid signals a non existent uid/gid.

diff --git a/source3/passdb/lookup_sid.c b/source3/passdb/lookup_sid.c
index 5cf391f..930c5d1 100644
--- a/source3/passdb/lookup_sid.c
+++ b/source3/passdb/lookup_sid.c
@@ -1490,7 +1490,22 @@ bool sids_to_unix_ids(const struct dom_sid *sids, uint32_t num_sids,
 			continue;
 		}
 	}
+
 done:
+	for (i=0; i<num_sids; i++) {
+		switch(ids[i].type) {
+		case WBC_ID_TYPE_GID:
+			if (ids[i].id.gid == (gid_t)-1) {
+				ids[i].type = WBC_ID_TYPE_NOT_SPECIFIED;
+			}
+			break;
+		case WBC_ID_TYPE_UID:
+                        if (ids[i].id.uid == (uid_t)-1) {
+                                ids[i].type = WBC_ID_TYPE_NOT_SPECIFIED;
+                        }
+                        break;
+		}
+	}
 	ret = true;
 fail:
 	TALLOC_FREE(wbc_ids);