[B.A.T.M.A.N.] [PATCH 3/4] batman-adv: Fix reference counting of vlan object for tt_local_entry

Antonio Quartulli
2016-04-30T17:06:02Z

From: Sven Eckelmann <sven@narfation.org>

The batadv_tt_local_entry was specific to a batadv_softif_vlan and held an
implicit reference to it. But this reference was never stored in form of a
pointer in the tt_local_entry itself. Instead batadv_tt_local_remove,
batadv_tt_local_table_free and batadv_tt_local_purge_pending_clients depend
on a consistent state of bat_priv->softif_vlan_list and that
batadv_softif_vlan_get always returns the batadv_softif_vlan object which
it has a reference for. But batadv_softif_vlan_get cannot guarantee that
because it is working only with rcu_read_lock on this list. It can
therefore happen that an vid is in this list twice or that
batadv_softif_vlan_get cannot find the batadv_softif_vlan for an vid due to
some other list operations taking place at the same time.

Instead add a batadv_softif_vlan pointer directly in batadv_tt_local_entry
which will be used for the reference counter decremented on release of
batadv_tt_local_entry.

Fixes: 35df3b298fc8 ("batman-adv: fix TT VLAN inconsistency on VLAN re-add")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Acked-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
---
net/batman-adv/translation-table.c | 42 ++++----------------------------------
net/batman-adv/types.h | 2 ++
2 files changed, 6 insertions(+), 38 deletions(-)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index 0b43e86328a5..9b4551a86535 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -215,6 +215,8 @@ static void batadv_tt_local_entry_release(struct kref *ref)
tt_local_entry = container_of(ref, struct batadv_tt_local_entry,
common.refcount);

+ batadv_softif_vlan_put(tt_local_entry->vlan);
+
kfree_rcu(tt_local_entry, common.rcu);
}

@@ -673,6 +675,7 @@ bool batadv_tt_local_add(struct net_device *soft_iface, const u8 *addr,
kref_get(&tt_local->common.refcount);
tt_local->last_seen = jiffies;
tt_local->common.added_at = tt_local->last_seen;
+ tt_local->vlan = vlan;

/* the batman interface mac and multicast addresses should never be
* purged
@@ -991,7 +994,6 @@ int batadv_tt_local_seq_print_text(struct seq_file *seq, void *offset)
struct batadv_tt_common_entry *tt_common_entry;
struct batadv_tt_local_entry *tt_local;
struct batadv_hard_iface *primary_if;
- struct batadv_softif_vlan *vlan;
struct hlist_head *head;
unsigned short vid;
u32 i;
@@ -1027,14 +1029,6 @@ int batadv_tt_local_seq_print_text(struct seq_file *seq, void *offset)
last_seen_msecs = last_seen_msecs % 1000;

no_purge = tt_common_entry->flags & np_flag;
-
- vlan = batadv_softif_vlan_get(bat_priv, vid);
- if (!vlan) {
- seq_printf(seq, "Cannot retrieve VLAN %d\n",
- BATADV_PRINT_VID(vid));
- continue;
- }
-
seq_printf(seq,
" * %pM %4i [%c%c%c%c%c%c] %3u.%03u (%#.8x)\n",
tt_common_entry->addr,
@@ -1052,9 +1046,7 @@ int batadv_tt_local_seq_print_text(struct seq_file *seq, void *offset)
BATADV_TT_CLIENT_ISOLA) ? 'I' : '.'),
no_purge ? 0 : last_seen_secs,
no_purge ? 0 : last_seen_msecs,
- vlan->tt.crc);
-
- batadv_softif_vlan_put(vlan);
+ tt_local->vlan->tt.crc);
}
rcu_read_unlock();
}
@@ -1099,7 +1091,6 @@ u16 batadv_tt_local_remove(struct batadv_priv *bat_priv, const u8 *addr,
{
struct batadv_tt_local_entry *tt_local_entry;
u16 flags, curr_flags = BATADV_NO_FLAGS;
- struct batadv_softif_vlan *vlan;
void *tt_entry_exists;

tt_local_entry = batadv_tt_local_hash_find(bat_priv, addr, vid);
@@ -1139,14 +1130,6 @@ u16 batadv_tt_local_remove(struct batadv_priv *bat_priv, const u8 *addr,
/* extra call to free the local tt entry */
batadv_tt_local_entry_put(tt_local_entry);

- /* decrease the reference held for this vlan */
- vlan = batadv_softif_vlan_get(bat_priv, vid);
- if (!vlan)
- goto out;
-
- batadv_softif_vlan_put(vlan);
- batadv_softif_vlan_put(vlan);
-
out:
if (tt_local_entry)
batadv_tt_local_entry_put(tt_local_entry);
@@ -1219,7 +1202,6 @@ static void batadv_tt_local_table_free(struct batadv_priv *bat_priv)
spinlock_t *list_lock; /* protects write access to the hash lists */
struct batadv_tt_common_entry *tt_common_entry;
struct batadv_tt_local_entry *tt_local;
- struct batadv_softif_vlan *vlan;
struct hlist_node *node_tmp;
struct hlist_head *head;
u32 i;
@@ -1241,14 +1223,6 @@ static void batadv_tt_local_table_free(struct batadv_priv *bat_priv)
struct batadv_tt_local_entry,
common);

- /* decrease the reference held for this vlan */
- vlan = batadv_softif_vlan_get(bat_priv,
- tt_common_entry->vid);
- if (vlan) {
- batadv_softif_vlan_put(vlan);
- batadv_softif_vlan_put(vlan);
- }
-
batadv_tt_local_entry_put(tt_local);
}
spin_unlock_bh(list_lock);
@@ -3309,7 +3283,6 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
struct batadv_hashtable *hash = bat_priv->tt.local_hash;
struct batadv_tt_common_entry *tt_common;
struct batadv_tt_local_entry *tt_local;
- struct batadv_softif_vlan *vlan;
struct hlist_node *node_tmp;
struct hlist_head *head;
spinlock_t *list_lock; /* protects write access to the hash lists */
@@ -3339,13 +3312,6 @@ static void batadv_tt_local_purge_pending_clients(struct batadv_priv *bat_priv)
struct batadv_tt_local_entry,
common);

- /* decrease the reference held for this vlan */
- vlan = batadv_softif_vlan_get(bat_priv, tt_common->vid);
- if (vlan) {
- batadv_softif_vlan_put(vlan);
- batadv_softif_vlan_put(vlan);
- }
-
batadv_tt_local_entry_put(tt_local);
}
spin_unlock_bh(list_lock);
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 443e9b84e07d..65afd090ab3e 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -1073,10 +1073,12 @@ struct batadv_tt_common_entry {
* struct batadv_tt_local_entry - translation table local entry data
* @common: general translation table data
* @last_seen: timestamp used for purging stale tt local entries
+ * @vlan: soft-interface vlan of the entry
*/
struct batadv_tt_local_entry {
struct batadv_tt_common_entry common;
unsigned long last_seen;
+ struct batadv_softif_vlan *vlan;
};

/**
--
2.8.1