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: 6529eab ("net: sched: introduce tcf block infractructure") Signed-off-by: Konstantin Khlebnikov <[email protected]> Acked-by: Jiri Pirko <[email protected]> Signed-off-by: David S. Miller <[email protected]>
berg · Aug 16, 2017 · 8989042 · 8989042
1 parent 187e5b3
commit 8989042
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Showing 4 changed files with 12 additions and 4 deletions.
diff --git 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
@@ -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
@@ -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
@@ -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],