[SRU][B][PATCH 5/7] net_sched: fix a memory leak in cls_tcindex

[Andrea Righi]

From: Cong Wang <xiyou.wangcong at gmail.com>

Buglink: https://bugs.launchpad.net/bugs/1825942

When tcindex_destroy() destroys all the filter results in
the perfect hash table, it invokes the walker to delete
each of them. However, results with class==0 are skipped
in either tcindex_walk() or tcindex_delete(), which causes
a memory leak reported by kmemleak.

This patch fixes it by skipping the walker and directly
deleting these filter results so we don't miss any filter
result.

As a result of this change, we have to initialize exts->net
properly in tcindex_alloc_perfect_hash(). For net-next, we
need to consider whether we should initialize ->net in
tcf_exts_init() instead, before that just directly test
CONFIG_NET_CLS_ACT=y.

Cc: Jamal Hadi Salim <jhs at mojatatu.com>
Cc: Jiri Pirko <jiri at resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(backported from commit 033b228e7f26b29ae37f8bfa1bc6b209a5365e9f)
Signed-off-by: Andrea Righi <andrea.righi at canonical.com>
---
 net/sched/cls_tcindex.c | 46 +++++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 16 deletions(-)

diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
index 5d89ca5c76cd..13164d8d055a 100644
--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -220,14 +220,6 @@ static int tcindex_delete(struct tcf_proto *tp, void *arg, bool *last)
 	return 0;
 }
 
-static int tcindex_destroy_element(struct tcf_proto *tp,
-				   void *arg, struct tcf_walker *walker)
-{
-	bool last;
-
-	return tcindex_delete(tp, arg, &last);
-}
-
 static void tcindex_destroy_work(struct work_struct *work)
 {
 	struct tcindex_data *p = container_of(to_rcu_work(work),
@@ -278,7 +270,7 @@ static void tcindex_free_perfect_hash(struct tcindex_data *cp)
 	kfree(cp->perfect);
 }
 
-static int tcindex_alloc_perfect_hash(struct tcindex_data *cp)
+static int tcindex_alloc_perfect_hash(struct net *net, struct tcindex_data *cp)
 {
 	int i, err = 0;
 
@@ -292,6 +284,9 @@ static int tcindex_alloc_perfect_hash(struct tcindex_data *cp)
 				    TCA_TCINDEX_ACT, TCA_TCINDEX_POLICE);
 		if (err < 0)
 			goto errout;
+#ifdef CONFIG_NET_CLS_ACT
+		cp->perfect[i].exts.net = net;
+#endif
 	}
 
 	return 0;
@@ -340,7 +335,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
 	if (p->perfect) {
 		int i;
 
-		if (tcindex_alloc_perfect_hash(cp) < 0)
+		if (tcindex_alloc_perfect_hash(net, cp) < 0)
 			goto errout;
 		for (i = 0; i < cp->hash; i++)
 			cp->perfect[i].res = p->perfect[i].res;
@@ -409,7 +404,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base,
 	err = -ENOMEM;
 	if (!cp->perfect && !cp->h) {
 		if (valid_perfect_hash(cp)) {
-			if (tcindex_alloc_perfect_hash(cp) < 0)
+			if (tcindex_alloc_perfect_hash(net, cp) < 0)
 				goto errout_alloc;
 			balloc = 1;
 		} else {
@@ -562,13 +557,32 @@ static void tcindex_walk(struct tcf_proto *tp, struct tcf_walker *walker)
 static void tcindex_destroy(struct tcf_proto *tp)
 {
 	struct tcindex_data *p = rtnl_dereference(tp->root);
-	struct tcf_walker walker;
+	int i;
 
 	pr_debug("tcindex_destroy(tp %p),p %p\n", tp, p);
-	walker.count = 0;
-	walker.skip = 0;
-	walker.fn = tcindex_destroy_element;
-	tcindex_walk(tp, &walker);
+
+	if (p->perfect) {
+		for (i = 0; i < p->hash; i++) {
+			struct tcindex_filter_result *r = p->perfect + i;
+
+			tcf_unbind_filter(tp, &r->res);
+			if (tcf_exts_get_net(&r->exts))
+				tcf_queue_work(&r->rwork,
+					       tcindex_destroy_rexts_work);
+			else
+				__tcindex_destroy_rexts(r);
+		}
+	}
+
+	for (i = 0; p->h && i < p->hash; i++) {
+		struct tcindex_filter *f, *next;
+		bool last;
+
+		for (f = rtnl_dereference(p->h[i]); f; f = next) {
+			next = rtnl_dereference(f->next);
+			tcindex_delete(tp, &f->result, &last);
+		}
+	}
 
 	tcf_queue_work(&p->rwork, tcindex_destroy_work);
 }
-- 
2.17.1