From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Date: Tue, 15 Aug 2017 13:35:21 +0000 (+0300)
Subject: net_sched: reset pointers to tcf blocks in classful qdiscs' destructors
X-Git-Tag: v4.14-rc1~283^2~5
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=898904226b5a6dee657f23cf51e385f50da22596;p=platform%2Fkernel%2Flinux-rpi.git

net_sched: reset pointers to tcf blocks in classful qdiscs' destructors

Traffic filters could keep direct pointers to classes in classful qdisc,
thus qdisc destruction first removes all filters before freeing classes.
Class destruction methods also tries to free attached filters but now
this isn't safe because tcf_block_put() unlike to tcf_destroy_chain()
cannot be called second time.

This patch set class->block to NULL after first tcf_block_put() and
turn second call into no-op.

Fixes: 6529eaba33f0 ("net: sched: introduce tcf block infractructure")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c
index 572fe25..c403c87 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -572,8 +572,10 @@ static void atm_tc_destroy(struct Qdisc *sch)
 	struct atm_flow_data *flow, *tmp;
 
 	pr_debug("atm_tc_destroy(sch %p,[qdisc %p])\n", sch, p);
-	list_for_each_entry(flow, &p->flows, list)
+	list_for_each_entry(flow, &p->flows, list) {
 		tcf_block_put(flow->block);
+		flow->block = NULL;
+	}
 
 	list_for_each_entry_safe(flow, tmp, &p->flows, list) {
 		if (flow->ref > 1)
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 481036f..780db43 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -1431,8 +1431,10 @@ static void cbq_destroy(struct Qdisc *sch)
 	 * be bound to classes which have been destroyed already. --TGR '04
 	 */
 	for (h = 0; h < q->clhash.hashsize; h++) {
-		hlist_for_each_entry(cl, &q->clhash.hash[h], common.hnode)
+		hlist_for_each_entry(cl, &q->clhash.hash[h], common.hnode) {
 			tcf_block_put(cl->block);
+			cl->block = NULL;
+		}
 	}
 	for (h = 0; h < q->clhash.hashsize; h++) {
 		hlist_for_each_entry_safe(cl, next, &q->clhash.hash[h],
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 3ad02bb..fd15200 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1530,8 +1530,10 @@ hfsc_destroy_qdisc(struct Qdisc *sch)
 	unsigned int i;
 
 	for (i = 0; i < q->clhash.hashsize; i++) {
-		hlist_for_each_entry(cl, &q->clhash.hash[i], cl_common.hnode)
+		hlist_for_each_entry(cl, &q->clhash.hash[i], cl_common.hnode) {
 			tcf_block_put(cl->block);
+			cl->block = NULL;
+		}
 	}
 	for (i = 0; i < q->clhash.hashsize; i++) {
 		hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 203286a..5d65ec5 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1258,8 +1258,10 @@ static void htb_destroy(struct Qdisc *sch)
 	tcf_block_put(q->block);
 
 	for (i = 0; i < q->clhash.hashsize; i++) {
-		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode)
+		hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
 			tcf_block_put(cl->block);
+			cl->block = NULL;
+		}
 	}
 	for (i = 0; i < q->clhash.hashsize; i++) {
 		hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],