From: Linus Lüssing <linus.luessing@xxxxxxxxx>
commit a3c7cd0cdf1107f891aff847ad481e34df727055 upstream.
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: syzbot+83f2d54ec6b7e417e13f@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+050927a651272b145a5d@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+979ffc89b87309b1b94b@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+f9f3f388440283da2965@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: cbebd363b2e9 ("batman-adv: Use own timer for multicast TT and TVLV updates")
Signed-off-by: Linus Lüssing <linus.luessing@xxxxxxxxx>
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Signed-off-by: Simon Wunderlich <sw@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/batman-adv/main.c | 1 +
net/batman-adv/multicast.c | 11 +++--------
net/batman-adv/types.h | 2 ++
3 files changed, 6 insertions(+), 8 deletions(-)
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -153,6 +153,7 @@ int batadv_mesh_init(struct net_device *
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);
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -269,8 +269,6 @@ static void batadv_mcast_mla_list_free(s
* 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)
@@ -278,8 +276,6 @@ static void batadv_mcast_mla_tt_retract(
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 &&
@@ -303,8 +299,6 @@ static void batadv_mcast_mla_tt_retract(
*
* 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)
@@ -312,8 +306,6 @@ static void batadv_mcast_mla_tt_add(stru
struct batadv_hw_addr *mcast_entry;
struct hlist_node *tmp;
- WARN_ON(delayed_work_pending(&bat_priv->mcast.work));
-
if (!mcast_list)
return;
@@ -600,7 +592,10 @@ static void batadv_mcast_mla_update(stru
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);
}
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -798,6 +798,7 @@ struct batadv_mcast_querier_state {
* @flags: the flags we have last sent in our mcast tvlv
* @enabled: whether the multicast tvlv is currently enabled
* @bridged: whether the soft interface has a bridge on top
+ * @mla_lock: a lock protecting mla_list and mla_flags
* @num_disabled: number of nodes that have no mcast tvlv
* @num_want_all_unsnoopables: number of nodes wanting unsnoopable IP traffic
* @num_want_all_ipv4: counter for items in want_all_ipv4_list
@@ -816,6 +817,7 @@ struct batadv_priv_mcast {
u8 flags;
bool enabled;
bool bridged;
+ spinlock_t mla_lock;
atomic_t num_disabled;
atomic_t num_want_all_unsnoopables;
atomic_t num_want_all_ipv4;
