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

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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>
This commit is contained in:
Linus Lüssing 2012-10-17 14:53:05 +02:00 committed by Antonio Quartulli
parent 7f112af40f
commit 7dac7b76b8
2 changed files with 16 additions and 5 deletions
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19
net/batman-adv/bridge_loop_avoidance.c
View File

@ -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;
}

2
net/batman-adv/types.h
View File

@ -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;
};