[PATCH net 3/9] batman-adv: bla: prevent CRC corruptions after claim flush

[Simon Wunderlich <sw@simonwunderlich.de>]

From: Sven Eckelmann <sven@narfation.org>

When batadv_bla_del_backbone_claims() tried to remove all claims of a
backbone, it sets the CRC to 0. It assumes that the it had the last
reference of the claims because batadv_claim_release() (which runs after
the last reference was released), is XORing the crc16 of the claim address
with the backbone CRC.

If there would be a parallel holder of any of these references, it could
happen that the backbone CRC is (0 ^ crc16(delayed_released_claim)). Which
is the wrong starting point for the new claims it may receive when the
remote answers the claim request from batadv_bla_send_request().

This reinitializations can be completely dropped to avoid this problem.
batadv_claim_release() will take care of fixing the backbone CRC.

Cc: stable@vger.kernel.org
Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/bridge_loop_avoidance.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index a3530cc90c959..3194ccdbce607 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -325,11 +325,6 @@ batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw)
 		}
 		spin_unlock_bh(list_lock);
 	}
-
-	/* all claims gone, initialize CRC */
-	spin_lock_bh(&backbone_gw->crc_lock);
-	backbone_gw->crc = BATADV_BLA_CRC_INIT;
-	spin_unlock_bh(&backbone_gw->crc_lock);
 }
 
 /**
-- 
2.47.3