From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E4044320CAD; Sat, 30 May 2026 17:57:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780163842; cv=none; b=KsSCBMLPA4oczuS2poCIsk6PQK2/BObmyvH3DcUQfE6uBB9VsA2odBUvMaw0S0pf8ClPsoXAATu4CD+bdzX9lgv5GWwIMO1zeWPuF0FH0TAGtQB1UEdMzmvb4U00y2mh33ePl1KxKeISMs3TdWy+WSCnrfFVGqjtvyrS/+JSHKc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780163842; c=relaxed/simple; bh=XJvwSbSJ90F3e8vn0b5C8hSjngoDMxTOoX1ItGmLQ7c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dhwK1TJe0QD1tN9lAdM4+h8neksX7P2lwupD0rLVDJtq4UELBWrfWET3iUOqVTtSSToBJl72rNyAq84hDmHiZoqokX742L2wpOCMbefiuFmCSmaohcRqnVynms43UIa4bK5mQtxT0qVh+jEVrCN8A2R55fqaXS9ep7Uqa3Xd8IQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0Atv1bO5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0Atv1bO5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 060581F00893; Sat, 30 May 2026 17:57:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780163841; bh=SEtebZvbyzFW6JNdCpufAYPbPRkCdODJTACic6QcLzI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=0Atv1bO5Viar0Pxzj8UJ4jRoMn5cF2R8OxkQuJJNG7o0uM3sL1YIwOpj0amc+7clD 76IqLy0vsrvFGZdHAHOYVOZiTeyERN2pQUmKuRwH06ejkicFOz+z1LSp2zn69dEK3Q MQt9qit5Z7ZFZeF78t41RZmGInSe7JS4swrio04c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Sven Eckelmann Subject: [PATCH 5.15 378/776] batman-adv: bla: only purge non-released claims Date: Sat, 30 May 2026 18:01:32 +0200 Message-ID: <20260530160250.293614831@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260530160240.228940103@linuxfoundation.org> References: <20260530160240.228940103@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sven Eckelmann commit cf6b604011591865ae39ac82de8978c1120d17af upstream. When batadv_bla_purge_claims() goes through the list of claims, it is only traversing the hash list with an rcu_read_lock(). Due to a potential parallel batadv_claim_put(), it can happen that it encounters a claim which was actually in the process of being released+freed by batadv_claim_release(). In this case, backbone_gw is set to NULL before the delayed RCU kfree is started. Calling batadv_bla_claim_get_backbone_gw() is then no longer allowed because it would cause a NULL-ptr derefence. To avoid this, only claims with a valid reference counter must be purged. All others are already taken care of. Cc: stable@kernel.org Fixes: 23721387c409 ("batman-adv: add basic bridge loop avoidance code") Signed-off-by: Sven Eckelmann Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/bridge_loop_avoidance.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/net/batman-adv/bridge_loop_avoidance.c +++ b/net/batman-adv/bridge_loop_avoidance.c @@ -1287,6 +1287,13 @@ static void batadv_bla_purge_claims(stru rcu_read_lock(); hlist_for_each_entry_rcu(claim, head, hash_entry) { + /* only purge claims not currently in the process of being released. + * Such claims could otherwise have a NULL-ptr backbone_gw set because + * they already went through batadv_claim_release() + */ + if (!kref_get_unless_zero(&claim->refcount)) + continue; + backbone_gw = batadv_bla_claim_get_backbone_gw(claim); if (now) goto purge_now; @@ -1312,6 +1319,7 @@ purge_now: claim->addr, claim->vid); skip: batadv_backbone_gw_put(backbone_gw); + batadv_claim_put(claim); } rcu_read_unlock(); }