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batman-adv: bla: fix freeing of claims on meshif deletion

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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: stable@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
2026-08-05 10:23:09 +02:00
parent 6a30a59e26
commit 8d128c932b
1 changed files with 1 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/batman-adv/bridge_loop_avoidance.c
+1 -9
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@@ -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;
}