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batman-adv: Fix reference counting of vlan object for tt_local_entry
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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: 35df3b2 ("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>
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Sven Eckelmann authored and Antonio Quartulli committed Apr 29, 2016
1 parent b6cf5d4 commit a33d970
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Showing 2 changed files with 6 additions and 38 deletions.
42 changes: 4 additions & 38 deletions net/batman-adv/translation-table.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}

Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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,
Expand All @@ -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();
}
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand All @@ -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);
Expand Down Expand Up @@ -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 */
Expand Down Expand Up @@ -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);
Expand Down
2 changes: 2 additions & 0 deletions net/batman-adv/types.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
};

/**
Expand Down

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