[PATCH 2/2] batman-adv: Fix potential broadcast BLA-duplicate-check race condition
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REVIEWED: 1 (0M)
From: Antonio Quartulli <hidden>
Date: 2012-10-18 19:25:43
Also in:
batman
Subsystem:
batman advanced, the rest · Maintainers:
Marek Lindner, Simon Wunderlich, Antonio Quartulli, Sven Eckelmann, Linus Torvalds
1 review trailer.
From: Linus Lüssing <redacted> 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 <redacted> Acked-by: Simon Wunderlich <redacted> Signed-off-by: Marek Lindner <redacted> Signed-off-by: Antonio Quartulli <redacted> --- 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 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; };
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1.7.12.3