batman-adv: bla: prevent CRC corruptions after claim flush

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: 23721387c4 ("batman-adv: add basic bridge loop avoidance code")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
This commit is contained in:
Sven Eckelmann 2026-07-05 22:21:50 +02:00
parent 08645ab957
commit 89f3502ff6
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@ -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);
}
/**