From: Haseeb Malik Creating a MACsec device with MAC offload over an LRO-capable lower device triggers a warning in rtmsg_ifinfo_build_skb() when IPv4 forwarding is enabled by default. register_netdevice() invokes inetdev_init(), which disables LRO and emits a NETDEV_FEAT_CHANGE notification. This reaches macsec_fill_info() before macsec_add_dev() initializes the SecY. key_len is still zero, so macsec_fill_info() returns -EMSGSIZE and trips the WARN_ON in rtmsg_ifinfo_build_skb(), even though the skb has enough space. Initialize the SecY and apply the new-link attributes before registration. Move MAC address inheritance into macsec_newlink() so the SCI can also be initialized before registration-time notifications report it. Move the per-CPU statistics and metadata destination allocation into ndo_init(), and release partial allocations on failure. Fixes: ccfdec908922 ("macsec: Add support for GCM-AES-256 cipher suite") Reported-by: syzbot+f2f6312ad1b5a0bfe316@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f2f6312ad1b5a0bfe316 Suggested-by: Sabrina Dubroca Link: https://lists.openwall.net/linux-kernel/2026/08/19/552 Signed-off-by: Haseeb Malik --- Changes in v2: - Initialize the SCI before registration, including MAC address inheritance, so registration-time notifications carry the configured SCI. - Wrap the per-CPU statistics allocation at 80 columns. - Link to v1: https://lore.kernel.org/netdev/20260911-fix-macsec-net-v1-1-c82aa58ae741@gmail.com/ --- drivers/net/macsec.c | 84 +++++++++++++++++++++++++++------------------------- 1 file changed, 43 insertions(+), 41 deletions(-) diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c index 6f9f3aceffaa..78a19b134632 100644 --- a/drivers/net/macsec.c +++ b/drivers/net/macsec.c @@ -3539,6 +3539,22 @@ static int macsec_dev_init(struct net_device *dev) if (err) return err; + err = -ENOMEM; + macsec->stats = netdev_alloc_pcpu_stats(struct pcpu_secy_stats); + if (!macsec->stats) + goto destroy_gro_cells; + + macsec->secy.tx_sc.stats = + netdev_alloc_pcpu_stats(struct pcpu_tx_sc_stats); + if (!macsec->secy.tx_sc.stats) + goto free_secy_stats; + + macsec->secy.tx_sc.md_dst = metadata_dst_alloc(0, METADATA_MACSEC, + GFP_KERNEL); + if (!macsec->secy.tx_sc.md_dst) + goto free_tx_sc_stats; + macsec->secy.tx_sc.md_dst->u.macsec_info.sci = macsec->secy.sci; + macsec_inherit_tso_max(dev); dev->hw_features = real_dev->hw_features & MACSEC_OFFLOAD_FEATURES; @@ -3551,8 +3567,6 @@ static int macsec_dev_init(struct net_device *dev) macsec_set_head_tail_room(dev); - if (is_zero_ether_addr(dev->dev_addr)) - eth_hw_addr_inherit(dev, real_dev); if (is_zero_ether_addr(dev->broadcast)) memcpy(dev->broadcast, real_dev->broadcast, dev->addr_len); @@ -3560,6 +3574,14 @@ static int macsec_dev_init(struct net_device *dev) netdev_hold(real_dev, &macsec->dev_tracker, GFP_KERNEL); return 0; + +free_tx_sc_stats: + free_percpu(macsec->secy.tx_sc.stats); +free_secy_stats: + free_percpu(macsec->stats); +destroy_gro_cells: + gro_cells_destroy(&macsec->gro_cells); + return err; } static void macsec_dev_uninit(struct net_device *dev) @@ -4116,26 +4138,11 @@ static sci_t dev_to_sci(struct net_device *dev, __be16 port) return make_sci(dev->dev_addr, port); } -static int macsec_add_dev(struct net_device *dev, sci_t sci, u8 icv_len) +static void macsec_init_secy(struct net_device *dev, sci_t sci, u8 icv_len) { struct macsec_dev *macsec = macsec_priv(dev); struct macsec_secy *secy = &macsec->secy; - macsec->stats = netdev_alloc_pcpu_stats(struct pcpu_secy_stats); - if (!macsec->stats) - return -ENOMEM; - - secy->tx_sc.stats = netdev_alloc_pcpu_stats(struct pcpu_tx_sc_stats); - if (!secy->tx_sc.stats) - return -ENOMEM; - - secy->tx_sc.md_dst = metadata_dst_alloc(0, METADATA_MACSEC, GFP_KERNEL); - if (!secy->tx_sc.md_dst) - /* macsec and secy percpu stats will be freed when unregistering - * net_device in macsec_free_netdev() - */ - return -ENOMEM; - if (sci == MACSEC_UNDEF_SCI) sci = dev_to_sci(dev, MACSEC_PORT_ES); @@ -4149,15 +4156,12 @@ static int macsec_add_dev(struct net_device *dev, sci_t sci, u8 icv_len) secy->xpn = DEFAULT_XPN; secy->sci = sci; - secy->tx_sc.md_dst->u.macsec_info.sci = sci; secy->tx_sc.active = true; secy->tx_sc.encoding_sa = DEFAULT_ENCODING_SA; secy->tx_sc.encrypt = DEFAULT_ENCRYPT; secy->tx_sc.send_sci = DEFAULT_SEND_SCI; secy->tx_sc.end_station = false; secy->tx_sc.scb = false; - - return 0; } static struct lock_class_key macsec_netdev_addr_lock_key; @@ -4220,6 +4224,24 @@ static int macsec_newlink(struct net_device *dev, if (rx_handler && rx_handler != macsec_handle_frame) return -EBUSY; + if (is_zero_ether_addr(dev->dev_addr)) + eth_hw_addr_inherit(dev, real_dev); + + if (data && data[IFLA_MACSEC_SCI]) + sci = nla_get_sci(data[IFLA_MACSEC_SCI]); + else if (data && data[IFLA_MACSEC_PORT]) + sci = dev_to_sci(dev, nla_get_be16(data[IFLA_MACSEC_PORT])); + else + sci = dev_to_sci(dev, MACSEC_PORT_ES); + + /* Registration can notify listeners before returning. */ + macsec_init_secy(dev, sci, icv_len); + if (data) { + err = macsec_changelink_common(dev, data); + if (err) + return err; + } + err = register_netdevice(dev); if (err < 0) return err; @@ -4232,31 +4254,11 @@ static int macsec_newlink(struct net_device *dev, if (err < 0) goto unregister; - /* need to be already registered so that ->init has run and - * the MAC addr is set - */ - if (data && data[IFLA_MACSEC_SCI]) - sci = nla_get_sci(data[IFLA_MACSEC_SCI]); - else if (data && data[IFLA_MACSEC_PORT]) - sci = dev_to_sci(dev, nla_get_be16(data[IFLA_MACSEC_PORT])); - else - sci = dev_to_sci(dev, MACSEC_PORT_ES); - if (rx_handler && sci_exists(real_dev, sci)) { err = -EBUSY; goto unlink; } - err = macsec_add_dev(dev, sci, icv_len); - if (err) - goto unlink; - - if (data) { - err = macsec_changelink_common(dev, data); - if (err) - goto del_dev; - } - /* If h/w offloading is available, propagate to the device */ if (macsec_is_offloaded(macsec)) { const struct macsec_ops *ops; --- base-commit: 78445023439506ebd83b86d40b1e428a3b309d4a change-id: 20260911-fix-macsec-net-ff3bc5e7ab0a Best regards, -- Haseeb Malik