linux.git/drivers/net/bonding, branch master

bonding: 3ad: fix mux port state on oper down

2026-06-10T14:53:36+00:00

When the bonding interface has carrier down due to the absence of
usable slaves and a slave transitions from down to up, the bonding
interface briefly goes carrier up, then down again, and finally up
once LACP negotiates collecting and distributing on the port.

When lacp_strict mode is on, the interface should not transition to
carrier up until LACP negotiation is complete.

This happens because the actor and partner port states remain in
Collecting_Distributing when the port goes down. When the port
comes back up, it temporarily remains in this state until LACP
renegotiation occurs.

Previously this was mostly cosmetic, but since the bonding carrier
state may depend on the LACP negotiation state, it causes the
interface to flap.

According to IEEE 802.3ad-2000 and IEEE 802.1ax-2014, Collecting and
Distributing should be reset when a port goes down:
- In the Receive state machine, port_enabled == FALSE causes a
  transition to the PORT_DISABLED state, which is expected to clear
  Partner_Oper_Port_State.Synchronization.
- In the Mux state machine, Partner_Oper_Port_State.Synchronization ==
  FALSE causes a transition to the ATTACHED state, which disables
  Collecting and Distributing.

However, Partner_Oper_Port_State.Synchronization is not cleared in the
PORT_DISABLED state.

Clear Partner_Oper_Port_State.Synchronization in the Receive
PORT_DISABLED state.

Fixes: 655f8919d549 ("bonding: add min links parameter to 802.3ad")
Signed-off-by: Louis Scalbert 
Acked-by: Jay Vosburgh 
Link: https://patch.msgid.link/20260603150331.1919611-6-louis.scalbert@6wind.com
Signed-off-by: Jakub Kicinski

bonding: 3ad: fix carrier when no usable slaves

2026-06-10T14:53:33+00:00

Apply the "lacp_strict" configuration from the previous commit.

"lacp_strict" mode "on" asserts that the bonding master carrier is up
only when at least 'min_links' slaves are in the Collecting_Distributing
state.

Fixes: 655f8919d549 ("bonding: add min links parameter to 802.3ad")
Signed-off-by: Louis Scalbert 
Acked-by: Jay Vosburgh 
Link: https://patch.msgid.link/20260603150331.1919611-5-louis.scalbert@6wind.com
Signed-off-by: Jakub Kicinski

bonding: 3ad: add lacp_strict configuration knob

2026-06-10T14:53:26+00:00

When an 802.3ad (LACP) bonding interface has no slaves in the
collecting/distributing state, the bonding master still reports
carrier as up as long as at least 'min_links' slaves have carrier.

In this situation, only one slave is effectively used for TX/RX,
while traffic received on other slaves is dropped. Upper-layer
daemons therefore consider the interface operational, even though
traffic may be blackholed if the lack of LACP negotiation means
the partner is not ready to deal with traffic.

Introduce a configuration knob to control this behavior. It allows
the bonding master to assert carrier only when at least 'min_links'
slaves are in Collecting_Distributing state.

The default mode preserves the existing behavior. This patch only
introduces the knob; its behavior is implemented in the subsequent
commit.

Fixes: 655f8919d549 ("bonding: add min links parameter to 802.3ad")
Signed-off-by: Louis Scalbert 
Acked-by: Jay Vosburgh 
Link: https://patch.msgid.link/20260603150331.1919611-4-louis.scalbert@6wind.com
Signed-off-by: Jakub Kicinski

bonding: annotate data-races in sysfs and procfs

2026-06-05T01:03:07+00:00

bonding sysfs and procfs read parameters locklessly,
while drivers/net/bonding/bond_options.c can write over them.

Add missing READ_ONCE()/WRITE_ONCE() annotations.

This came as a prereq to avoid RTNL in bond_fill_info().

Signed-off-by: Eric Dumazet 
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/20260602152748.2564393-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2026-06-04T22:29:04+00:00

Cross-merge networking fixes after downstream PR (net-7.1-rc7).

Silent conflicts:

net/wireless/nl80211.c
  cb9959ab5f99 ("wifi: cfg80211: enforce HE/EHT cap/oper consistency")
  a384ae969902 ("wifi: cfg80211: move AP HT/VHT/... operation to beacon info")
https://lore.kernel.org/aiGJDaHV4UlCexIQ@sirena.org.uk

Conflicts:

drivers/net/wireless/intel/iwlwifi/mld/ap.c
  a342c99cb70d ("wifi: iwlwifi: mld: honor BSS_CHANGED_BEACON_ENABLED")
  9bf1b409afc7 ("wifi: iwlwifi: mld: send tx power constraints before link activation")
https://lore.kernel.org/ah2bfedhV45ZxMO8@sirena.org.uk

drivers/net/wireless/intel/iwlwifi/pcie/drv.c
  093305d801fa ("wifi: iwlwifi: pcie: simplify the resume flow if fast resume is not used")
  e2323929a68a ("wifi: iwlwifi: pcie: add debug print for resume flow if powered off")
https://lore.kernel.org/ah2bfedhV45ZxMO8@sirena.org.uk

Adjacent changes:

drivers/net/ethernet/airoha/airoha_eth.c
  b38cae85d1c4 ("net: airoha: Fix use-after-free in metadata dst teardown")
  ec6c391bcca7 ("net: airoha: Introduce airoha_gdm_dev struct")

drivers/net/ethernet/microchip/lan743x_main.c
  8173d22b211f ("net: lan743x: permit VLAN-tagged packets up to configured MTU")
  e3c6508a46f5 ("net: lan743x: avoid netdev-based logging before netdev registration")

Signed-off-by: Jakub Kicinski

net: bonding: don't recurse on the slave's netdev ops lock

2026-06-04T21:04:55+00:00

bond_update_speed_duplex() calls __ethtool_get_link_ksettings() on
the slave, which will soon take the slave's ops lock. One of its
callers already holds it and the other three don't, so the function
would either deadlock or run unprotected depending on the path.

Make the helper expect the slave's ops lock held and switch to
netif_get_link_ksettings(). Wrap the three call sites that don't
already hold it:

  * bond_enslave() (rtnl held; core drops the lower's ops lock
    around ->ndo_add_slave).
  * bond_miimon_commit() (rtnl_trylock'd from the mii workqueue).
  * bond_ethtool_get_link_ksettings() (rtnl held via ethtool layer,
    bond device itself is not ops locked).

The call site which does already hold the ops lock is
bond_slave_netdev_event() via NETDEV_UP / NETDEV_CHANGE notifiers,
so it stays as-is.

Reviewed-by: Nicolai Buchwitz 
Link: https://patch.msgid.link/20260603012840.2254293-6-kuba@kernel.org
Signed-off-by: Jakub Kicinski

bonding: annotate data-races arcound churn variables

2026-06-04T15:58:18+00:00

These fields are updated asynchronously by the bonding state machine
in ad_churn_machine() while holding bond->mode_lock.

bond_info_show_slave() and bond_fill_slave_info() read them without
bond->mode_lock being held, we need to add READ_ONCE() and
WRITE_ONCE() annotations.

Note that AD_CHURN_MONITOR, AD_CHURN, and AD_NO_CHURN are defined
exclusively in (kernel private) include/net/bond_3ad.h header.

They should be moved to include/uapi/linux/if_bonding.h or userspace
tools will have to hardcode their values.

Fixes: 4916f2e2f3fc ("bonding: print churn state via netlink")
Fixes: 14c9551a32eb ("bonding: Implement port churn-machine (AD standard 43.4.17).")
Signed-off-by: Eric Dumazet 
Link: https://patch.msgid.link/20260603123514.388226-1-edumazet@google.com
Signed-off-by: Jakub Kicinski

net: bonding: fix NULL pointer dereference in bond_do_ioctl()

2026-06-04T09:38:51+00:00

In bond_do_ioctl(), slave_dev is obtained via __dev_get_by_name() which
can return NULL if the requested interface name does not exist. However,
the subsequent slave_dbg() call is placed before the NULL check:

    slave_dev = __dev_get_by_name(net, ifr->ifr_slave);
    slave_dbg(bond_dev, slave_dev, "slave_dev=%p:\n", slave_dev); //here
    if (!slave_dev)
        return -ENODEV;

The slave_dbg() macro expands to netdev_dbg(bond_dev, "(slave %s): " fmt,
(slave_dev)->name, ...) which unconditionally dereferences slave_dev->name
before the NULL check is performed. This results in a NULL pointer
dereference kernel oops when a user calls bonding ioctl (e.g.
SIOCBONDENSLAVE, SIOCBONDRELEASE, etc.) with a non-existent slave
interface name.

This is reachable from userspace via the bonding ioctl interface with
CAP_NET_ADMIN capability, making it a potential local denial-of-service
vector.

Fix by moving the slave_dbg() call after the NULL check.

Fixes: e2a7420df2e0 ("bonding/main: convert to using slave printk macros")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: ZhaoJinming 
Link: https://patch.msgid.link/20260601085649.4029067-1-zhaojinming@uniontech.com
Signed-off-by: Paolo Abeni

bonding: refuse to enslave CAN devices

2026-05-27T23:58:28+00:00

syzbot reported a kernel paging request crash in
can_rx_unregister() inside net/can/af_can.c. The crash occurs
because a virtual CAN device (vxcan) is being enslaved to a
bonding master.

During the enslavement process, the bonding driver mutates
and modifies the network device states to fit an Ethernet-like
aggregation model. However, CAN devices operate on a completely
different Layer 2 architecture, relying on the CAN mid-layer
private data structure (can_ml_priv) instead of standard
Ethernet structures. Since bonding does not initialize or
maintain these CAN structures, subsequent operations on the
half-enslaved interface (such as closing associated sockets
via isotp_release) lead to a null-pointer dereference when
accessing the CAN receiver lists.

Bonding CAN interfaces is architecturally invalid as CAN lacks
MAC addresses, ARP capabilities, and standard Ethernet
link-layer mechanisms. While generic loopback devices are
blocked globally in net/core/dev.c, virtual CAN devices
bypass this check because they do not carry the IFF_LOOPBACK
flag, despite acting as local software-loopbacks.

Fix this by explicitly blocking network devices of type
ARPHRD_CAN from being enslaved at the very beginning of
bond_enslave(). This prevents illegal state mutations,
eliminates the resulting KASAN crashes, and avoids potential
memory leaks from incomplete socket cleanups.

As the CAN support has been added a long time after bonding
the Fixes-tag points to the introduction of ARPHRD_CAN that
would have needed a specific handling in bonding_main.c.

Fixes: cd05acfe65ed ("[CAN]: Allocate protocol numbers for PF_CAN")
Reported-by: syzbot+8ed98cbd0161632bce95@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8ed98cbd0161632bce95
Signed-off-by: Oliver Hartkopp 
Acked-by: Jay Vosburgh 
Link: https://patch.msgid.link/20260526-bonding-candev-v1-1-ba1df400918a@hartkopp.net
Signed-off-by: Jakub Kicinski

bonding: 3ad: implement proper RCU rules for port->aggregator

2026-04-30T01:32:02+00:00

syzbot found a data-race in bond_3ad_get_active_agg_info /
bond_3ad_state_machine_handler [1] which hints at lack of proper
RCU implementation.

Add __rcu qualifier to port->aggregator, and add proper RCU API.

[1]

BUG: KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler

write to 0xffff88813cf5c4b0 of 8 bytes by task 36 on cpu 0:
  ad_port_selection_logic drivers/net/bonding/bond_3ad.c:1659 [inline]
  bond_3ad_state_machine_handler+0x9d5/0x2d60 drivers/net/bonding/bond_3ad.c:2569
  process_one_work kernel/workqueue.c:3302 [inline]
  process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3385
  worker_thread+0x58a/0x780 kernel/workqueue.c:3466
  kthread+0x22a/0x280 kernel/kthread.c:436
  ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88813cf5c4b0 of 8 bytes by task 22063 on cpu 1:
  __bond_3ad_get_active_agg_info drivers/net/bonding/bond_3ad.c:2858 [inline]
  bond_3ad_get_active_agg_info+0x8c/0x230 drivers/net/bonding/bond_3ad.c:2881
  bond_fill_info+0xe0f/0x10f0 drivers/net/bonding/bond_netlink.c:853
  rtnl_link_info_fill net/core/rtnetlink.c:906 [inline]
  rtnl_link_fill+0x1d7/0x4e0 net/core/rtnetlink.c:927
  rtnl_fill_ifinfo+0xf8e/0x1380 net/core/rtnetlink.c:2168
  rtmsg_ifinfo_build_skb+0x11c/0x1b0 net/core/rtnetlink.c:4453
  rtmsg_ifinfo_event net/core/rtnetlink.c:4486 [inline]
  rtmsg_ifinfo+0x6d/0x110 net/core/rtnetlink.c:4495
  __dev_notify_flags+0x76/0x390 net/core/dev.c:9790
  netif_change_flags+0xac/0xd0 net/core/dev.c:9823
  do_setlink+0x905/0x2950 net/core/rtnetlink.c:3180
  rtnl_group_changelink net/core/rtnetlink.c:3813 [inline]
  __rtnl_newlink net/core/rtnetlink.c:3981 [inline]
  rtnl_newlink+0xf55/0x1400 net/core/rtnetlink.c:4109
  rtnetlink_rcv_msg+0x64b/0x720 net/core/rtnetlink.c:6995
  netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
  rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:7022
  netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
  netlink_unicast+0x5a8/0x680 net/netlink/af_netlink.c:1344
  netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894
  sock_sendmsg_nosec net/socket.c:787 [inline]
  __sock_sendmsg net/socket.c:802 [inline]
  ____sys_sendmsg+0x563/0x5b0 net/socket.c:2698
  ___sys_sendmsg+0x195/0x1e0 net/socket.c:2752
  __sys_sendmsg net/socket.c:2784 [inline]
  __do_sys_sendmsg net/socket.c:2789 [inline]
  __se_sys_sendmsg net/socket.c:2787 [inline]
  __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2787
  x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88813cf5c400

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 22063 Comm: syz.0.31122 Tainted: G        W           syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026

Fixes: 47e91f56008b ("bonding: use RCU protection for 3ad xmit path")
Reported-by: syzbot+9bb2ff2a4ab9e17307e1@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/69f0a82f.050a0220.3aadc4.0000.GAE@google.com/
Signed-off-by: Eric Dumazet 
Cc: Jay Vosburgh 
Cc: Andrew Lunn 
Link: https://patch.msgid.link/20260428123207.3809211-1-edumazet@google.com
Signed-off-by: Jakub Kicinski