From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793207747; b=mWj0AYjt2wDW27iqPa5+0TWiRP5fx/m/u4lkZNXlQ6uX2dPjOIK4t9dfU7+rRsVusYUG QU3fHIXJCtNHz7x+syPbbjgm8eXPGgl44iFtJrTv/uFDXl/dEplx9j30R42by7o/h8vh6 /i4ePch4/Ex/et+2xc0G7FoG72ir1Ozp4PUGQqphvO0iIwmONLQVF1LIxd7TDywsAZ0wH GrFwHLFWKYr33OrF+54+RSSXmvLJz1hzNUKgHAMENbAo62+l9m5hk6agIjxG6xi/BIj5Y Qf1B+QAng1pF9032+lbORrb7OhfI8qhf8AQvuj/2kXthAx1qWJpXZhE0bj3z5ZSxqcQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793207747; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=6KAMN5J9XJhUgVz1lmK4ISJqTBeScZhMn5/5opUL7hI=; b=PcjcChBw7rjg0N3y3NU8x48z13CaUSCL8+0PoFOvvDmFBwyfrwyegyTzQZiJHsltxHPv f0/+NHyzm42kUw7O/eqx2Nmq8EqIH96wNop7QfB+ZFJ43PYHe14eBvwPOmBmL1pn/VOgd 7asOTqr9HnaEOUoGL571ZPCtiEDigDqg9rpshCPg3rTQyVXc5y0jMlUphL8NVAEcba2MV v3Gm8N0RhUIBlYDhT8jCXFQ4FuYi08GViBN9cGgFKnIgrgotJBZhWRKjtMqgJaXGl4yTT 380ce8i1AwGVE35DxOrN909jT3JguiS8vrvTvYzxYubwXW6RvmYtj8pJgX2zjtBbEeg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b="Rh1hz/WS"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 32E5A606A31D; Wed, 28 Oct 2026 17:15:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=Rh1hz/WS Received: by smtp.kernel.org (Postfix) with ESMTPSA id 84A7B1F031E0; Wed, 28 Oct 2026 17:15:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793207747; bh=6KAMN5J9XJhUgVz1lmK4ISJqTBeScZhMn5/5opUL7hI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Rh1hz/WSV/70ZxXGqfIiPswzKF7ZwRczBNfqBs5hiSjs9NoooaLzU6uNSK6QUxHcW jkqfTNLzDKgw6l+Nua3SQq8j9Dd7cnkvX95FuQSTRua970o2oRdA8xFhr6gMCjcxIc pzVOVNOXiM9mkF7HIuy06RCPOYuJMA2yaqX5O2lA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nikolay Aleksandrov , TencentOS Corvus AI , Jun Yang , Jakub Kicinski Subject: [PATCH 6.12 123/247] net: bridge: mcast: dont truncate the port group walk on teardown Date: Wed, 28 Oct 2026 17:58:46 +0100 Message-ID: <20261028165950.315365716@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165947.349197979@linuxfoundation.org> References: <20261028165947.349197979@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jun Yang commit 5a3f7a683aee56e1f15c9d53041f3236767eaae7 upstream. __br_multicast_disable_port_ctx() and br_multicast_del_port() walk port->mglist with hlist_for_each_entry_safe(). However, br_multicast_find_del_pg() can also delete other entries from the same list through br_multicast_fwd_src_remove() or __fwd_del_star_excl(). If such an entry is the iterator's saved next node, hlist_del_init() clears its ->next and terminates the walk early. The reproducer triggers this in both teardown walks, leaving port groups in the bridge mdb with a dangling ->key.port after del_nbp() frees the port: BUG: KASAN: slab-use-after-free in __mdb_fill_info+0x1191/0x1320 __mdb_fill_info+0x1191/0x1320 br_mdb_dump+0x594/0xe40 rtnl_mdb_dump+0x1cf/0x5d0 Use hlist_del_init_rcu() to unlink the group while preserving ->next. br_multicast_del_pg() and the teardown walks run under br->multicast_lock. The GC worker must acquire the same lock before detaching the group for destruction, so the node remains alive while the walk uses the preserved pointer. Preserving ->next means a walk can now reach a group that an earlier iteration already deleted as a side effect. That group is off mp->ports, so br_multicast_find_del_pg() would fall through its port scan and hit the trailing WARN_ON(1). Skip such groups at the top of that helper: a port group is put on port->mglist when it is created and only unlinked when it is deleted, so hlist_unhashed() identifies exactly this case. Fixes: b08123684bd5 ("net: bridge: mcast: install S,G entries automatically based on reports") Cc: stable@vger.kernel.org Suggested-by: Nikolay Aleksandrov Reported-by: TencentOS Corvus AI Signed-off-by: Jun Yang Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260831111330.199543-1-junvyyang@tencent.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/bridge/br_multicast.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -813,7 +813,11 @@ static void __br_multicast_del_pg(struct struct hlist_node *tmp; rcu_assign_pointer(*pp, pg->next); - hlist_del_init(&pg->mglist); + /* Keep ->next (held under multicast_lock, freed later by the GC work): + * a port->mglist teardown walk may have latched this node as its next, + * and deleting other groups of the same port must not truncate it. + */ + hlist_del_init_rcu(&pg->mglist); br_multicast_eht_clean_sets(pg); hlist_for_each_entry_safe(ent, tmp, &pg->src_list, node) br_multicast_del_group_src(ent, false); @@ -848,6 +852,13 @@ static void br_multicast_find_del_pg(str struct net_bridge_mdb_entry *mp; struct net_bridge_port_group *p; + /* A teardown walk over port->mglist can reach a group that an earlier + * iteration already deleted as a side effect. It is off mp->ports by + * now, so skip it instead of falling through to the WARN_ON() below. + */ + if (hlist_unhashed(&pg->mglist)) + return; + mp = br_mdb_ip_get(br, &pg->key.addr); if (WARN_ON(!mp)) return;