[PATCH] Fix memleak bug 13362

Volker Lendecke Volker.Lendecke at SerNet.DE
Mon May 14 18:45:58 UTC 2018


Hi!

Reporter confirmed it fixes the issue. Thanks to Szombathelyi György
<gyurco at freemail.hu> for the logs and tests.

Review appreciated!

Thanks, Volker

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de, mailto:kontakt at sernet.de
-------------- next part --------------
From 2818b6a221776d4d1ab0ee5e880260c22781e1ac Mon Sep 17 00:00:00 2001
From: Volker Lendecke <vl at samba.org>
Date: Mon, 7 May 2018 16:41:55 +0200
Subject: [PATCH 1/2] lib: Put "results_store" into a doubly linked list

Bug: https://bugzilla.samba.org/show_bug.cgi?id=13362
Signed-off-by: Volker Lendecke <vl at samba.org>
---
 lib/ldb/modules/paged_results.c | 25 +++++--------------------
 1 file changed, 5 insertions(+), 20 deletions(-)

diff --git a/lib/ldb/modules/paged_results.c b/lib/ldb/modules/paged_results.c
index de014a39699..aafbcbf4483 100644
--- a/lib/ldb/modules/paged_results.c
+++ b/lib/ldb/modules/paged_results.c
@@ -35,6 +35,7 @@
 #include "replace.h"
 #include "system/filesys.h"
 #include "system/time.h"
+#include "dlinklist.h"
 #include "ldb_module.h"
 
 struct message_store {
@@ -48,14 +49,13 @@ struct message_store {
 struct private_data;
 
 struct results_store {
+	struct results_store *prev, *next;
 
 	struct private_data *priv;
 
 	char *cookie;
 	time_t timestamp;
 
-	struct results_store *next;
-
 	struct message_store *first;
 	struct message_store *last;
 	int num_entries;
@@ -75,22 +75,8 @@ struct private_data {
 static int store_destructor(struct results_store *del)
 {
 	struct private_data *priv = del->priv;
-	struct results_store *loop;
-
-	if (priv->store == del) {
-		priv->store = del->next;
-		return 0;
-	}
-
-	for (loop = priv->store; loop; loop = loop->next) {
-		if (loop->next == del) {
-			loop->next = del->next;
-			return 0;
-		}
-	}
-
-	/* is not in list ? */
-	return -1;
+	DLIST_REMOVE(priv->store, del);
+	return 0;
 }
 
 static struct results_store *new_store(struct private_data *priv)
@@ -120,8 +106,7 @@ static struct results_store *new_store(struct private_data *priv)
 	newr->first_ref = NULL;
 	newr->controls = NULL;
 
-	newr->next = priv->store;
-	priv->store = newr;
+	DLIST_ADD(priv->store, newr);
 
 	talloc_set_destructor(newr, store_destructor);
 
-- 
2.11.0


From 90ebf48be88806ec48c90b860519138a9932617c Mon Sep 17 00:00:00 2001
From: Volker Lendecke <vl at samba.org>
Date: Mon, 7 May 2018 16:53:00 +0200
Subject: [PATCH 2/2] lib: Hold at most 10 outstanding paged result cookies

Bug: https://bugzilla.samba.org/show_bug.cgi?id=13362
Signed-off-by: Volker Lendecke <vl at samba.org>
---
 lib/ldb/modules/paged_results.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/lib/ldb/modules/paged_results.c b/lib/ldb/modules/paged_results.c
index aafbcbf4483..ecb22271d28 100644
--- a/lib/ldb/modules/paged_results.c
+++ b/lib/ldb/modules/paged_results.c
@@ -36,6 +36,7 @@
 #include "system/filesys.h"
 #include "system/time.h"
 #include "dlinklist.h"
+#include <assert.h>
 #include "ldb_module.h"
 
 struct message_store {
@@ -68,6 +69,7 @@ struct results_store {
 
 struct private_data {
 	uint32_t next_free_id;
+	size_t num_stores;
 	struct results_store *store;
 	
 };
@@ -76,6 +78,10 @@ static int store_destructor(struct results_store *del)
 {
 	struct private_data *priv = del->priv;
 	DLIST_REMOVE(priv->store, del);
+
+	assert(priv->num_stores > 0);
+	priv->num_stores -= 1;
+
 	return 0;
 }
 
@@ -108,8 +114,21 @@ static struct results_store *new_store(struct private_data *priv)
 
 	DLIST_ADD(priv->store, newr);
 
+	assert(priv->num_stores < SIZE_MAX);
+	priv->num_stores += 1;
+
 	talloc_set_destructor(newr, store_destructor);
 
+	if (priv->num_stores > 10) {
+		struct results_store *last;
+		/*
+		 * 10 is the default for MaxResultSetsPerConn --
+		 * possibly need to parameterize it.
+		 */
+		last = DLIST_TAIL(priv->store);
+		TALLOC_FREE(last);
+	}
+
 	return newr;
 }
 
@@ -366,6 +385,8 @@ static int paged_search(struct ldb_module *module, struct ldb_request *req)
 			return LDB_ERR_UNWILLING_TO_PERFORM;
 		}
 
+		DLIST_PROMOTE(private_data->store, current);
+
 		ac->store = current;
 
 		/* check if it is an abandon */
@@ -397,6 +418,7 @@ static int paged_request_init(struct ldb_module *module)
 	}
 
 	data->next_free_id = 1;
+	data->num_stores = 0;
 	data->store = NULL;
 	ldb_module_set_private(module, data);
 
-- 
2.11.0



More information about the samba-technical mailing list