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Miller" Subject: [PATCH 6.1 0463/1887] net: bridge: avoid recursive multicast port cleanup Date: Wed, 28 Oct 2026 17:42:39 +0100 Message-ID: <20261028170509.770752166@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zixuan Chai commit 5158353121bae4f552cb677ce8c5c3ef52f93a0d upstream. br_multicast_sg_del_exclude_ports() removes automatically added STAR_EXCL port groups by calling br_multicast_del_pg(). For S,G entries, that deletion calls back into br_multicast_sg_del_exclude_ports(), so a large number of STAR_EXCL ports consumes one kernel stack frame per port and can hit the stack guard page. Keep the complete port-group deletion path for cleanup, but suppress the S,G exclude-port cleanup while that helper is already walking the same entry. Normal deletion callers retain the existing behavior. Fixes: 8266a0491e92 ("net: bridge: mcast: handle port group filter modes") Cc: stable@vger.kernel.org Reported-by: Vega Assisted-by: LLM Signed-off-by: Zixuan Chai Signed-off-by: Ren Wei Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/bridge/br_multicast.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -80,6 +80,10 @@ __br_multicast_add_group(struct net_brid bool blocked); static void br_multicast_find_del_pg(struct net_bridge *br, struct net_bridge_port_group *pg); +static void __br_multicast_del_pg(struct net_bridge_mdb_entry *mp, + struct net_bridge_port_group *pg, + struct net_bridge_port_group __rcu **pp, + bool sg_del_exclude_ports); static void __br_multicast_stop(struct net_bridge_mcast *brmctx); static int br_mc_disabled_update(struct net_device *dev, bool value, @@ -436,7 +440,7 @@ static void br_multicast_sg_del_exclude_ for (pp = &sgmp->ports; (p = mlock_dereference(*pp, sgmp->br)) != NULL;) { if (!(p->flags & MDB_PG_FLAGS_PERMANENT)) - br_multicast_del_pg(sgmp, p, pp); + __br_multicast_del_pg(sgmp, p, pp, false); else pp = &p->next; } @@ -675,9 +679,10 @@ static void br_multicast_destroy_port_gr kfree_rcu(pg, rcu); } -void br_multicast_del_pg(struct net_bridge_mdb_entry *mp, - struct net_bridge_port_group *pg, - struct net_bridge_port_group __rcu **pp) +static void __br_multicast_del_pg(struct net_bridge_mdb_entry *mp, + struct net_bridge_port_group *pg, + struct net_bridge_port_group __rcu **pp, + bool sg_del_exclude_ports) { struct net_bridge *br = pg->key.port->br; struct net_bridge_group_src *ent; @@ -692,7 +697,8 @@ void br_multicast_del_pg(struct net_brid if (!br_multicast_is_star_g(&mp->addr)) { rhashtable_remove_fast(&br->sg_port_tbl, &pg->rhnode, br_sg_port_rht_params); - br_multicast_sg_del_exclude_ports(mp); + if (sg_del_exclude_ports) + br_multicast_sg_del_exclude_ports(mp); } else { br_multicast_star_g_handle_mode(pg, MCAST_INCLUDE); } @@ -703,6 +709,13 @@ void br_multicast_del_pg(struct net_brid mod_timer(&mp->timer, jiffies); } +void br_multicast_del_pg(struct net_bridge_mdb_entry *mp, + struct net_bridge_port_group *pg, + struct net_bridge_port_group __rcu **pp) +{ + __br_multicast_del_pg(mp, pg, pp, true); +} + static void br_multicast_find_del_pg(struct net_bridge *br, struct net_bridge_port_group *pg) {