[PATCH net 9/9] batman-adv: bla: fix freeing of claims on meshif deletion

From: Sven Eckelmann <[email protected]>

When the mesh interface is getting deleted, then
batadv_bla_del_backbone_claims() (via batadv_bla_purge_backbone_gw()) could
make sure that all claims gets removed. But this function is only executed
when bat_priv->bla.claim_hash is not NULL. And since batadv_bla_free() is
always setting it to NULL before it is (indirectly) called, it was never
actually executed.

But the batadv_bla_purge_claims() -> batadv_handle_unclaim() is at the
moment too fragile because the BLA code is not handling the rehashing in
batadv_bla_update_orig_address(). The stored backbone address doesn't have
to be the one actually used for the hash bucket selection during the
initial adding of the backbone. The batadv_handle_unclaim() can therefore
fail to find the respective backbone for the unclaim and then stop the
deletion.

But the actual backbone_gw object is not needed for the unclaim because all
relevant information is always provided by the caller. And the check for
the existence of the backbone_gw doesn't provide any additional security
check for the deletion of a claim.

Cc: [email protected]
Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code")
Signed-off-by: Sven Eckelmann <[email protected]>
Signed-off-by: Simon Wunderlich <[email protected]>
---
 net/batman-adv/bridge_loop_avoidance.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 3194ccdbce607..f635da4b8ca65 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -950,26 +950,18 @@ static bool batadv_handle_unclaim(struct batadv_priv *bat_priv,
 				  const u8 *backbone_addr, const u8 *claim_addr,
 				  unsigned short vid)
 {
-	struct batadv_bla_backbone_gw *backbone_gw;
-
 	/* unclaim in any case if it is our own */
 	if (primary_if && batadv_compare_eth(backbone_addr,
 					     primary_if->net_dev->dev_addr))
 		batadv_bla_send_claim(bat_priv, claim_addr, vid,
 				      BATADV_CLAIM_TYPE_UNCLAIM);
 
-	backbone_gw = batadv_backbone_hash_find(bat_priv, backbone_addr, vid);
-
-	if (!backbone_gw)
-		return true;
-
 	/* this must be an UNCLAIM frame */
 	batadv_dbg(BATADV_DBG_BLA, bat_priv,
 		   "%s(): UNCLAIM %pM on vid %d (sent by %pM)...\n", __func__,
-		   claim_addr, batadv_print_vid(vid), backbone_gw->orig);
+		   claim_addr, batadv_print_vid(vid), backbone_addr);
 
 	batadv_bla_del_claim(bat_priv, claim_addr, vid);
-	batadv_backbone_gw_put(backbone_gw);
 	return true;
 }
 
-- 
2.47.3