netdev - Re: [PATCH] team: avoid NETDEV_CHANGEMTU event when unregistering slave

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4mtehfz7kbb7xcygrcb4rbmmy7clr7qomnrd3wv6byfd7muwf2@5qgpxozmi3ja>
Date: Tue, 27 Jan 2026 08:38:54 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc: Ido Schimmel <idosch@...dia.com>, Breno Leitao <leitao@...ian.org>, 
	"David S. Miller" <davem@...emloft.net>, David Ahern <dsahern@...nel.org>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH] team: avoid NETDEV_CHANGEMTU event when unregistering
 slave

Sun, Jan 25, 2026 at 03:35:28PM +0100, penguin-kernel@...ove.SAKURA.ne.jp wrote:
>syzbot is reporting
>
>  unregister_netdevice: waiting for netdevsim0 to become free. Usage count = 3
>  ref_tracker: netdev@...f88807dcf8618 has 1/2 users at
>       __netdev_tracker_alloc include/linux/netdevice.h:4400 [inline]
>       netdev_hold include/linux/netdevice.h:4429 [inline]
>       inetdev_init+0x201/0x4e0 net/ipv4/devinet.c:286
>       inetdev_event+0x251/0x1610 net/ipv4/devinet.c:1600
>       notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
>       call_netdevice_notifiers_mtu net/core/dev.c:2318 [inline]
>       netif_set_mtu_ext+0x5aa/0x800 net/core/dev.c:9886
>       netif_set_mtu+0xd7/0x1b0 net/core/dev.c:9907
>       dev_set_mtu+0x126/0x260 net/core/dev_api.c:248
>       team_port_del+0xb07/0xcb0 drivers/net/team/team_core.c:1333
>       team_del_slave drivers/net/team/team_core.c:1936 [inline]
>       team_device_event+0x207/0x5b0 drivers/net/team/team_core.c:2929
>       notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
>       call_netdevice_notifiers_extack net/core/dev.c:2281 [inline]
>       call_netdevice_notifiers net/core/dev.c:2295 [inline]
>       __dev_change_net_namespace+0xcb7/0x2050 net/core/dev.c:12592
>       do_setlink+0x2ce/0x4590 net/core/rtnetlink.c:3060
>       rtnl_changelink net/core/rtnetlink.c:3776 [inline]
>       __rtnl_newlink net/core/rtnetlink.c:3935 [inline]
>       rtnl_newlink+0x15a9/0x1be0 net/core/rtnetlink.c:4072
>       rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6958
>       netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
>       netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
>       netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
>       netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
>
>problem. Ido Schimmel found steps to reproduce
>
>  ip link add name team1 type team
>  ip link add name dummy1 mtu 1499 master team1 type dummy
>  ip netns add ns1
>  ip link set dev dummy1 netns ns1
>  ip -n ns1 link del dev dummy1
>
>and also found that the same issue was fixed in the bond driver in
>commit f51048c3e07b ("bonding: avoid NETDEV_CHANGEMTU event when
>unregistering slave").
>
>Let's do similar thing for the team driver, with commit ad7c7b2172c3 ("net:
>hold netdev instance lock during sysfs operations") and commit 303a8487a657
>("net: s/__dev_set_mtu/__netif_set_mtu/") also applied.
>
>Reported-by: syzbot+881d65229ca4f9ae8c84@...kaller.appspotmail.com
>Closes: https://syzkaller.appspot.com/bug?extid=881d65229ca4f9ae8c84
>Suggested-by: Ido Schimmel <idosch@...dia.com>
>Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>

Reviewed-by: Jiri Pirko <jiri@...dia.com>