Re: [syzbot] Re: BUG: corrupted list in ieee802154_if_remove

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Subject: Re: BUG: corrupted list in ieee802154_if_remove
Author: dmantipov@yandex.ru

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 906bd684e4b1e517dd424a354744c5b0aebef8af

diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h
index 08dd521a51a5..7afcea3447c1 100644
--- a/net/mac802154/ieee802154_i.h
+++ b/net/mac802154/ieee802154_i.h
@@ -40,9 +40,8 @@ struct ieee802154_local {
 	int open_count;
 
 	/* As in mac80211 slaves list is modified:
-	 * 1) under the RTNL
-	 * 2) protected by slaves_mtx;
-	 * 3) in an RCU manner
+	 * 1) under the RTNL;
+	 * 2) protected by iflist_mtx.
 	 *
 	 * So atomic readers can use any of this protection methods.
 	 */
@@ -101,6 +100,7 @@ enum {
 
 enum ieee802154_sdata_state_bits {
 	SDATA_STATE_RUNNING,
+	SDATA_STATE_REMOVED,
 };
 
 /* Slave interface definition.
diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c
index c0e2da5072be..700c80e94bb2 100644
--- a/net/mac802154/iface.c
+++ b/net/mac802154/iface.c
@@ -669,7 +669,7 @@ ieee802154_if_add(struct ieee802154_local *local, const char *name,
 		goto err;
 
 	mutex_lock(&local->iflist_mtx);
-	list_add_tail_rcu(&sdata->list, &local->interfaces);
+	list_add_tail(&sdata->list, &local->interfaces);
 	mutex_unlock(&local->iflist_mtx);
 
 	return ndev;
@@ -683,11 +683,13 @@ void ieee802154_if_remove(struct ieee802154_sub_if_data *sdata)
 {
 	ASSERT_RTNL();
 
+	if (test_and_set_bit(SDATA_STATE_REMOVED, &sdata->state))
+		return;
+
 	mutex_lock(&sdata->local->iflist_mtx);
-	list_del_rcu(&sdata->list);
+	list_del(&sdata->list);
 	mutex_unlock(&sdata->local->iflist_mtx);
 
-	synchronize_rcu();
 	unregister_netdevice(sdata->dev);
 }
 
@@ -697,6 +699,8 @@ void ieee802154_remove_interfaces(struct ieee802154_local *local)
 
 	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry_safe(sdata, tmp, &local->interfaces, list) {
+		if (test_and_set_bit(SDATA_STATE_REMOVED, &sdata->state))
+			continue;
 		list_del(&sdata->list);
 
 		unregister_netdevice(sdata->dev);
-- 
2.47.0