The following commit has been merged in the master branch: commit 7dac7b76b8db87fc79857a53a09730fb2148579b Author: Linus Lüssing linus.luessing@web.de Date: Wed Oct 17 14:53:05 2012 +0200

batman-adv: Fix potential broadcast BLA-duplicate-check race condition

Threads in the bottom half of batadv_bla_check_bcast_duplist() might otherwise for instance overwrite variables which other threads might be using/reading at the same time in the top half, potentially leading to messing up the bcast_duplist, possibly resulting in false bridge loop avoidance duplicate check decisions.

Signed-off-by: Linus Lüssing linus.luessing@web.de Acked-by: Simon Wunderlich siwu@hrz.tu-chemnitz.de Signed-off-by: Marek Lindner lindner_marek@yahoo.de

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index eebab20..fd8d5af 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -1167,6 +1167,8 @@ int batadv_bla_init(struct batadv_priv *bat_priv) uint16_t crc; unsigned long entrytime;

+ spin_lock_init(&bat_priv->bla.bcast_duplist_lock); + batadv_dbg(BATADV_DBG_BLA, bat_priv, "bla hash registering\n");

/* setting claim destination address */ @@ -1226,7 +1228,7 @@ int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, struct batadv_bcast_packet *bcast_packet, int bcast_packet_len) { - int i, length, curr; + int i, length, curr, ret = 0; uint8_t *content; uint16_t crc; struct batadv_bcast_duplist_entry *entry; @@ -1238,6 +1240,8 @@ int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, /* calculate the crc ... */ crc = crc16(0, content, length);

+ spin_lock_bh(&bat_priv->bla.bcast_duplist_lock); + for (i = 0; i < BATADV_DUPLIST_SIZE; i++) { curr = (bat_priv->bla.bcast_duplist_curr + i); curr %= BATADV_DUPLIST_SIZE; @@ -1259,9 +1263,12 @@ int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, /* this entry seems to match: same crc, not too old, * and from another gw. therefore return 1 to forbid it. */ - return 1; + ret = 1; + goto out; } - /* not found, add a new entry (overwrite the oldest entry) */ + /* not found, add a new entry (overwrite the oldest entry) + * and allow it, its the first occurence. + */ curr = (bat_priv->bla.bcast_duplist_curr + BATADV_DUPLIST_SIZE - 1); curr %= BATADV_DUPLIST_SIZE; entry = &bat_priv->bla.bcast_duplist[curr]; @@ -1270,8 +1277,10 @@ int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv, memcpy(entry->orig, bcast_packet->orig, ETH_ALEN); bat_priv->bla.bcast_duplist_curr = curr;

- /* allow it, its the first occurence. */ - return 0; +out: + spin_unlock_bh(&bat_priv->bla.bcast_duplist_lock); + + return ret; }

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 2ed82ca..ac1e07a 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -205,6 +205,8 @@ struct batadv_priv_bla { struct batadv_hashtable *backbone_hash; struct batadv_bcast_duplist_entry bcast_duplist[BATADV_DUPLIST_SIZE]; int bcast_duplist_curr; + /* protects bcast_duplist and bcast_duplist_curr */ + spinlock_t bcast_duplist_lock; struct batadv_bla_claim_dst claim_dest; struct delayed_work work; };