From: Sven Eckelmann sven@narfation.org
commit 3db0decf1185357d6ab2256d0dede1ca9efda03d upstream.
The pointer batadv_bla_claim::backbone_gw can be changed at any time. Therefore, access to it must be protected to ensure that two function accessing the same backbone_gw are actually accessing the same. This is especially important when the crc_lock is used or when the backbone_gw of a claim is exchanged.
Not doing so leads to invalid memory access and/or reference leaks.
Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Fixes: 5a1dd8a4773d ("batman-adv: lock crc access in bridge loop avoidance") Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Marek Lindner mareklindner@neomailbox.ch Signed-off-by: Simon Wunderlich sw@simonwunderlich.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/batman-adv/bridge_loop_avoidance.c | 112 ++++++++++++++++++++++++++------- net/batman-adv/types.h | 1 2 files changed, 90 insertions(+), 23 deletions(-)
--- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -129,7 +129,19 @@ batadv_backbone_gw_free_ref(struct batad /* finally deinitialize the claim */ static void batadv_claim_release(struct batadv_bla_claim *claim) { - batadv_backbone_gw_free_ref(claim->backbone_gw); + struct batadv_bla_backbone_gw *old_backbone_gw; + + spin_lock_bh(&claim->backbone_lock); + old_backbone_gw = claim->backbone_gw; + claim->backbone_gw = NULL; + spin_unlock_bh(&claim->backbone_lock); + + spin_lock_bh(&old_backbone_gw->crc_lock); + old_backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); + spin_unlock_bh(&old_backbone_gw->crc_lock); + + batadv_backbone_gw_free_ref(old_backbone_gw); + kfree_rcu(claim, rcu); }
@@ -579,8 +591,10 @@ static void batadv_bla_add_claim(struct const u8 *mac, const unsigned short vid, struct batadv_bla_backbone_gw *backbone_gw) { + struct batadv_bla_backbone_gw *old_backbone_gw; struct batadv_bla_claim *claim; struct batadv_bla_claim search_claim; + bool remove_crc = false; int hash_added;
ether_addr_copy(search_claim.addr, mac); @@ -594,8 +608,10 @@ static void batadv_bla_add_claim(struct return;
ether_addr_copy(claim->addr, mac); + spin_lock_init(&claim->backbone_lock); claim->vid = vid; claim->lasttime = jiffies; + atomic_inc(&backbone_gw->refcount); claim->backbone_gw = backbone_gw;
atomic_set(&claim->refcount, 2); @@ -622,15 +638,26 @@ static void batadv_bla_add_claim(struct "bla_add_claim(): changing ownership for %pM, vid %d\n", mac, BATADV_PRINT_VID(vid));
- spin_lock_bh(&claim->backbone_gw->crc_lock); - claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); - spin_unlock_bh(&claim->backbone_gw->crc_lock); - batadv_backbone_gw_free_ref(claim->backbone_gw); + remove_crc = true; } - /* set (new) backbone gw */ + + /* replace backbone_gw atomically and adjust reference counters */ + spin_lock_bh(&claim->backbone_lock); + old_backbone_gw = claim->backbone_gw; atomic_inc(&backbone_gw->refcount); claim->backbone_gw = backbone_gw; + spin_unlock_bh(&claim->backbone_lock);
+ if (remove_crc) { + /* remove claim address from old backbone_gw */ + spin_lock_bh(&old_backbone_gw->crc_lock); + old_backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); + spin_unlock_bh(&old_backbone_gw->crc_lock); + } + + batadv_backbone_gw_free_ref(old_backbone_gw); + + /* add claim address to new backbone_gw */ spin_lock_bh(&backbone_gw->crc_lock); backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); spin_unlock_bh(&backbone_gw->crc_lock); @@ -640,6 +667,26 @@ claim_free_ref: batadv_claim_free_ref(claim); }
+/** + * batadv_bla_claim_get_backbone_gw - Get valid reference for backbone_gw of + * claim + * @claim: claim whose backbone_gw should be returned + * + * Return: valid reference to claim::backbone_gw + */ +static struct batadv_bla_backbone_gw * +batadv_bla_claim_get_backbone_gw(struct batadv_bla_claim *claim) +{ + struct batadv_bla_backbone_gw *backbone_gw; + + spin_lock_bh(&claim->backbone_lock); + backbone_gw = claim->backbone_gw; + atomic_inc(&backbone_gw->refcount); + spin_unlock_bh(&claim->backbone_lock); + + return backbone_gw; +} + /* Delete a claim from the claim hash which has the * given mac address and vid. */ @@ -661,10 +708,6 @@ static void batadv_bla_del_claim(struct batadv_choose_claim, claim); batadv_claim_free_ref(claim); /* reference from the hash is gone */
- spin_lock_bh(&claim->backbone_gw->crc_lock); - claim->backbone_gw->crc ^= crc16(0, claim->addr, ETH_ALEN); - spin_unlock_bh(&claim->backbone_gw->crc_lock); - /* don't need the reference from hash_find() anymore */ batadv_claim_free_ref(claim); } @@ -1074,6 +1117,7 @@ static void batadv_bla_purge_claims(stru struct batadv_hard_iface *primary_if, int now) { + struct batadv_bla_backbone_gw *backbone_gw; struct batadv_bla_claim *claim; struct hlist_head *head; struct batadv_hashtable *hash; @@ -1088,14 +1132,17 @@ static void batadv_bla_purge_claims(stru
rcu_read_lock(); hlist_for_each_entry_rcu(claim, head, hash_entry) { + backbone_gw = batadv_bla_claim_get_backbone_gw(claim); if (now) goto purge_now; - if (!batadv_compare_eth(claim->backbone_gw->orig, + + if (!batadv_compare_eth(backbone_gw->orig, primary_if->net_dev->dev_addr)) - continue; + goto skip; + if (!batadv_has_timed_out(claim->lasttime, BATADV_BLA_CLAIM_TIMEOUT)) - continue; + goto skip;
batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla_purge_claims(): %pM, vid %d, time out\n", @@ -1103,8 +1150,10 @@ static void batadv_bla_purge_claims(stru
purge_now: batadv_handle_unclaim(bat_priv, primary_if, - claim->backbone_gw->orig, + backbone_gw->orig, claim->addr, claim->vid); +skip: + batadv_backbone_gw_free_ref(backbone_gw); } rcu_read_unlock(); } @@ -1488,9 +1537,11 @@ void batadv_bla_free(struct batadv_priv int batadv_bla_rx(struct batadv_priv *bat_priv, struct sk_buff *skb, unsigned short vid, bool is_bcast) { + struct batadv_bla_backbone_gw *backbone_gw; struct ethhdr *ethhdr; struct batadv_bla_claim search_claim, *claim = NULL; struct batadv_hard_iface *primary_if; + bool own_claim; int ret;
ethhdr = eth_hdr(skb); @@ -1522,8 +1573,12 @@ int batadv_bla_rx(struct batadv_priv *ba }
/* if it is our own claim ... */ - if (batadv_compare_eth(claim->backbone_gw->orig, - primary_if->net_dev->dev_addr)) { + backbone_gw = batadv_bla_claim_get_backbone_gw(claim); + own_claim = batadv_compare_eth(backbone_gw->orig, + primary_if->net_dev->dev_addr); + batadv_backbone_gw_free_ref(backbone_gw); + + if (own_claim) { /* ... allow it in any case */ claim->lasttime = jiffies; goto allow; @@ -1586,7 +1641,9 @@ int batadv_bla_tx(struct batadv_priv *ba { struct ethhdr *ethhdr; struct batadv_bla_claim search_claim, *claim = NULL; + struct batadv_bla_backbone_gw *backbone_gw; struct batadv_hard_iface *primary_if; + bool client_roamed; int ret = 0;
primary_if = batadv_primary_if_get_selected(bat_priv); @@ -1616,8 +1673,12 @@ int batadv_bla_tx(struct batadv_priv *ba goto allow;
/* check if we are responsible. */ - if (batadv_compare_eth(claim->backbone_gw->orig, - primary_if->net_dev->dev_addr)) { + backbone_gw = batadv_bla_claim_get_backbone_gw(claim); + client_roamed = batadv_compare_eth(backbone_gw->orig, + primary_if->net_dev->dev_addr); + batadv_backbone_gw_free_ref(backbone_gw); + + if (client_roamed) { /* if yes, the client has roamed and we have * to unclaim it. */ @@ -1670,6 +1731,7 @@ int batadv_bla_claim_table_seq_print_tex struct net_device *net_dev = (struct net_device *)seq->private; struct batadv_priv *bat_priv = netdev_priv(net_dev); struct batadv_hashtable *hash = bat_priv->bla.claim_hash; + struct batadv_bla_backbone_gw *backbone_gw; struct batadv_bla_claim *claim; struct batadv_hard_iface *primary_if; struct hlist_head *head; @@ -1694,17 +1756,21 @@ int batadv_bla_claim_table_seq_print_tex
rcu_read_lock(); hlist_for_each_entry_rcu(claim, head, hash_entry) { - is_own = batadv_compare_eth(claim->backbone_gw->orig, + backbone_gw = batadv_bla_claim_get_backbone_gw(claim); + + is_own = batadv_compare_eth(backbone_gw->orig, primary_addr);
- spin_lock_bh(&claim->backbone_gw->crc_lock); - backbone_crc = claim->backbone_gw->crc; - spin_unlock_bh(&claim->backbone_gw->crc_lock); + spin_lock_bh(&backbone_gw->crc_lock); + backbone_crc = backbone_gw->crc; + spin_unlock_bh(&backbone_gw->crc_lock); seq_printf(seq, " * %pM on %5d by %pM [%c] (%#.4x)\n", claim->addr, BATADV_PRINT_VID(claim->vid), - claim->backbone_gw->orig, + backbone_gw->orig, (is_own ? 'x' : ' '), backbone_crc); + + batadv_backbone_gw_free_ref(backbone_gw); } rcu_read_unlock(); } --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -917,6 +917,7 @@ struct batadv_bla_claim { u8 addr[ETH_ALEN]; unsigned short vid; struct batadv_bla_backbone_gw *backbone_gw; + spinlock_t backbone_lock; /* protects backbone_gw */ unsigned long lasttime; struct hlist_node hash_entry; struct rcu_head rcu;