From 7dac7b76b8db87fc79857a53a09730fb2148579b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@web.de>
Date: Wed, 17 Oct 2012 14:53:05 +0200
Subject: [PATCH] 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>
---
net/batman-adv/bridge_loop_avoidance.c | 19 ++++++++++++++-----
net/batman-adv/types.h | 2 ++
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index eebab20c7478c..fd8d5afec0ddb 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 2ed82caacdca4..ac1e07a804547 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;
};
--
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