Commit a3c7cd0c authored by Linus Lüssing's avatar Linus Lüssing Committed by Simon Wunderlich
Browse files

batman-adv: mcast: fix multicast tt/tvlv worker locking 



Syzbot has reported some issues with the locking assumptions made for
the multicast tt/tvlv worker: It was able to trigger the WARN_ON() in
batadv_mcast_mla_tt_retract() and batadv_mcast_mla_tt_add().
While hard/not reproduceable for us so far it seems that the
delayed_work_pending() we use might not be quite safe from reordering.

Therefore this patch adds an explicit, new spinlock to protect the
update of the mla_list and flags in bat_priv and then removes the
WARN_ON(delayed_work_pending()).

Reported-by: default avatar <syzbot+83f2d54ec6b7e417e13f@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+050927a651272b145a5d@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+979ffc89b87309b1b94b@syzkaller.appspotmail.com>
Reported-by: default avatar <syzbot+f9f3f388440283da2965@syzkaller.appspotmail.com>
Fixes: cbebd363 ("batman-adv: Use own timer for multicast TT and TVLV updates")
Signed-off-by: default avatarLinus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: default avatarSven Eckelmann <sven@narfation.org>
Signed-off-by: default avatarSimon Wunderlich <sw@simonwunderlich.de>
parent bdc76fd2

net/batman-adv/main.c

+1 −0
Original line number Diff line number Diff line
@@ -161,6 +161,7 @@ int batadv_mesh_init(struct net_device *soft_iface) 
	spin_lock_init(&bat_priv->tt.commit_lock);

	spin_lock_init(&bat_priv->gw.list_lock);

#ifdef CONFIG_BATMAN_ADV_MCAST

	spin_lock_init(&bat_priv->mcast.mla_lock);

	spin_lock_init(&bat_priv->mcast.want_lists_lock);

#endif

	spin_lock_init(&bat_priv->tvlv.container_list_lock);

net/batman-adv/multicast.c

+3 −8
Original line number Diff line number Diff line
@@ -325,8 +325,6 @@ static void batadv_mcast_mla_list_free(struct hlist_head *mcast_list) 
 * translation table except the ones listed in the given mcast_list.

 *

 * If mcast_list is NULL then all are retracted.

 *

 * Do not call outside of the mcast worker! (or cancel mcast worker first)

 */

static void batadv_mcast_mla_tt_retract(struct batadv_priv *bat_priv,

					struct hlist_head *mcast_list)
@@ -334,8 +332,6 @@ static void batadv_mcast_mla_tt_retract(struct batadv_priv *bat_priv, 
	struct batadv_hw_addr *mcast_entry;

	struct hlist_node *tmp;



	WARN_ON(delayed_work_pending(&bat_priv->mcast.work));



	hlist_for_each_entry_safe(mcast_entry, tmp, &bat_priv->mcast.mla_list,

				  list) {

		if (mcast_list &&
@@ -359,8 +355,6 @@ static void batadv_mcast_mla_tt_retract(struct batadv_priv *bat_priv, 
 *

 * Adds multicast listener announcements from the given mcast_list to the

 * translation table if they have not been added yet.

 *

 * Do not call outside of the mcast worker! (or cancel mcast worker first)

 */

static void batadv_mcast_mla_tt_add(struct batadv_priv *bat_priv,

				    struct hlist_head *mcast_list)
@@ -368,8 +362,6 @@ static void batadv_mcast_mla_tt_add(struct batadv_priv *bat_priv, 
	struct batadv_hw_addr *mcast_entry;

	struct hlist_node *tmp;



	WARN_ON(delayed_work_pending(&bat_priv->mcast.work));



	if (!mcast_list)

		return;
@@ -658,7 +650,10 @@ static void batadv_mcast_mla_update(struct work_struct *work) 
	priv_mcast = container_of(delayed_work, struct batadv_priv_mcast, work);

	bat_priv = container_of(priv_mcast, struct batadv_priv, mcast);



	spin_lock(&bat_priv->mcast.mla_lock);

	__batadv_mcast_mla_update(bat_priv);

	spin_unlock(&bat_priv->mcast.mla_lock);



	batadv_mcast_start_timer(bat_priv);

}

net/batman-adv/types.h

+5 −0
Original line number Diff line number Diff line
@@ -1223,6 +1223,11 @@ struct batadv_priv_mcast { 
	/** @bridged: whether the soft interface has a bridge on top */

	unsigned char bridged:1;



	/**

	 * @mla_lock: a lock protecting mla_list and mla_flags

	 */

	spinlock_t mla_lock;



	/**

	 * @num_want_all_unsnoopables: number of nodes wanting unsnoopable IP

	 *  traffic

CRA Git | Maintained and supported by SUSTech CRA and CCSE