From: Gary Lockyer <gary@catalyst.net.nz>
Date: Mon, 12 Mar 2018 19:10:54 +0000 (+1300)
Subject: ldb index: Fix truncation key length calculation
X-Git-Tag: ldb-1.4.0~708
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d161a6dcfef09ad939df76c5c77eb8b7519a9326;p=thirdparty%2Fsamba.git

ldb index: Fix truncation key length calculation

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
---

diff --git a/lib/ldb/ldb_tdb/ldb_index.c b/lib/ldb/ldb_tdb/ldb_index.c
index 076db10f2dd..ed28c4f642f 100644
--- a/lib/ldb/ldb_tdb/ldb_index.c
+++ b/lib/ldb/ldb_tdb/ldb_index.c
@@ -848,6 +848,19 @@ static struct ldb_dn *ltdb_index_key(struct ldb_context *ldb,
 	unsigned indx_len = 0;
 	unsigned frmt_len = 0;
 
+	if (max_key_length < 4) {
+		ldb_asprintf_errstring(
+			ldb,
+			__location__ ": max_key_length of (%u) < 4",
+			max_key_length);
+		return NULL;
+	}
+	/*
+	 * ltdb_key_dn() makes something 4 bytes longer, it adds a leading
+	 * "DN=" and a trailing string terninator
+	 */
+	max_key_length -= 4;
+
 	if (attr[0] == '@') {
 		attr_for_dn = attr;
 		v = *value;
@@ -911,12 +924,13 @@ static struct ldb_dn *ltdb_index_key(struct ldb_context *ldb,
 	if (should_b64_encode) {
 		unsigned vstr_len = 0;
 		char *vstr = ldb_base64_encode(ldb, (char *)v.data, v.length);
+		unsigned num_separators = 3;
 		if (!vstr) {
 			talloc_free(attr_folded);
 			return NULL;
 		}
 		vstr_len = strlen(vstr);
-		key_len = 3 + indx_len + attr_len + vstr_len;
+		key_len = num_separators + indx_len + attr_len + vstr_len;
 		if (key_len > max_key_length) {
 			unsigned excess = key_len - max_key_length;
 			frmt_len = vstr_len - excess;
@@ -943,7 +957,8 @@ static struct ldb_dn *ltdb_index_key(struct ldb_context *ldb,
 		}
 		talloc_free(vstr);
 	} else {
-		key_len = 2 + indx_len + attr_len + (int)v.length;
+		unsigned num_separators = 2;
+		key_len = num_separators + indx_len + attr_len + (int)v.length;
 		if (key_len > max_key_length) {
 			unsigned excess = key_len - max_key_length;
 			frmt_len = v.length - excess;
diff --git a/lib/ldb/tests/python/index.py b/lib/ldb/tests/python/index.py
index e9eaaf059e1..1d66ee930d1 100755
--- a/lib/ldb/tests/python/index.py
+++ b/lib/ldb/tests/python/index.py
@@ -113,11 +113,14 @@ class MaxIndexKeyLengthTests(LdbBaseTest):
         super(MaxIndexKeyLengthTests, self).setUp()
         self.testdir = tempdir()
         self.filename = os.path.join(self.testdir, "key_len_test.ldb")
-        # Note that the maximum key length is set to 50
+        # Note that the maximum key length is set to 54
+        # This accounts for the 4 bytes added by the dn formatting
+        # a leading dn=, and a trailing zero terminator
+        #
         self.l = ldb.Ldb(self.url(),
                          options=[
                              "modules:rdn_name",
-                             "max_key_len_for_self_test:50"])
+                             "max_key_len_for_self_test:54"])
         self.l.add({"dn": "@ATTRIBUTES",
                     "uniqueThing": "UNIQUE_INDEX"})
         self.l.add({"dn": "@INDEXLIST",