From 4ae1709a314060a196981b344610d023ea841e57 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Wed, 6 May 2026 22:20:50 +0200 Subject: [PATCH] batman-adv: bla: prevent use-after-free when deleting claims When batadv_bla_del_backbone_claims() removes all claims for a backbone, it does this by dropping the link entry in the hash list. This list entry itself was one of the references which need to be dropped at the same time via batadv_claim_put(). But the batadv_claim_put() must not be done before the last access to the claim object in this function. Otherwise the claim might be freed already by the batadv_claim_release() function before the list entry was dropped. Cc: stable@kernel.org Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Signed-off-by: Sven Eckelmann --- net/batman-adv/bridge_loop_avoidance.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c index 51fe028b9088..8b77dd2ecfa4 100644 --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -318,8 +318,8 @@ batadv_bla_del_backbone_claims(struct batadv_bla_backbone_gw *backbone_gw) if (claim->backbone_gw != backbone_gw) continue; - batadv_claim_put(claim); hlist_del_rcu(&claim->hash_entry); + batadv_claim_put(claim); } spin_unlock_bh(list_lock); }