linux-kernel - [PATCH net] team: grab team lock during team_change_rx

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Message-ID: <20250514220319.3505158-1-stfomichev@gmail.com>
Date: Wed, 14 May 2025 15:03:19 -0700
From: Stanislav Fomichev <stfomichev@...il.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	jiri@...nulli.us,
	andrew+netdev@...n.ch,
	sdf@...ichev.me,
	linux-kernel@...r.kernel.org,
	syzbot+53485086a41dbb43270a@...kaller.appspotmail.com
Subject: [PATCH net] team: grab team lock during team_change_rx_flags

Syzkaller reports the following issue:
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:578

 netdev_lock include/linux/netdevice.h:2751 [inline]
 netdev_lock_ops include/net/netdev_lock.h:42 [inline]
 dev_set_promiscuity+0x10e/0x260 net/core/dev_api.c:285
 bond_set_promiscuity drivers/net/bonding/bond_main.c:922 [inline]
 bond_change_rx_flags+0x219/0x690 drivers/net/bonding/bond_main.c:4732
 dev_change_rx_flags net/core/dev.c:9145 [inline]
 __dev_set_promiscuity+0x3f5/0x590 net/core/dev.c:9189
 netif_set_promiscuity+0x50/0xe0 net/core/dev.c:9201
 dev_set_promiscuity+0x126/0x260 net/core/dev_api.c:286
 ^^ all of the above is under rcu lock
 team_change_rx_flags+0x1b3/0x330 drivers/net/team/team_core.c:1785
 dev_change_rx_flags net/core/dev.c:9145 [inline]
 __dev_set_promiscuity+0x3f5/0x590 net/core/dev.c:9189
 netif_set_promiscuity+0x50/0xe0 net/core/dev.c:9201
 dev_set_promiscuity+0x126/0x260 net/core/dev_api.c:286
 hsr_del_port+0x25e/0x2d0 net/hsr/hsr_slave.c:233
 hsr_netdev_notify+0x827/0xb60 net/hsr/hsr_main.c:104
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
 call_netdevice_notifiers net/core/dev.c:2228 [inline]
 unregister_netdevice_many_notify+0x15d8/0x2330 net/core/dev.c:11970
 rtnl_delete_link net/core/rtnetlink.c:3522 [inline]
 rtnl_dellink+0x488/0x710 net/core/rtnetlink.c:3564
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883

team_change_rx_flags runs under rcu lock which means we can't grab
instance lock for the lower devices. Switch to team->lock, similar
to what we already do for team_set_mac_address and team_change_mtu.

Fixes: 78cd408356fe ("net: add missing instance lock to dev_set_promiscuity")
Reported-by: syzbot+53485086a41dbb43270a@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=53485086a41dbb43270a
Link: https://lore.kernel.org/netdev/6822cc81.050a0220.f2294.00e8.GAE@google.com
Signed-off-by: Stanislav Fomichev <stfomichev@...il.com>
---
 drivers/net/team/team_core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c
index d8fc0c79745d..b75ceb90359f 100644
--- a/drivers/net/team/team_core.c
+++ b/drivers/net/team/team_core.c
@@ -1778,8 +1778,8 @@ static void team_change_rx_flags(struct net_device *dev, int change)
 	struct team_port *port;
 	int inc;
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(port, &team->port_list, list) {
+	mutex_lock(&team->lock);
+	list_for_each_entry(port, &team->port_list, list) {
 		if (change & IFF_PROMISC) {
 			inc = dev->flags & IFF_PROMISC ? 1 : -1;
 			dev_set_promiscuity(port->dev, inc);
@@ -1789,7 +1789,7 @@ static void team_change_rx_flags(struct net_device *dev, int change)
 			dev_set_allmulti(port->dev, inc);
 		}
 	}
-	rcu_read_unlock();
+	mutex_unlock(&team->lock);
 }
 
 static void team_set_rx_mode(struct net_device *dev)
-- 
2.49.0