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 @@
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 @@
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 @@
/* 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 @@
/* 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 @@
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;
}