macsec: avoid to set wrong mtu (7f327080) · Commits · 戴 / test

When a macsec interface is created, the mtu is calculated with the lower interface's mtu value. If the mtu of lower interface is lower than the length, which is needed by macsec interface, macsec's mtu value will be overflowed. So, if the lower interface's mtu is too low, macsec interface's mtu should be set to 0. Test commands: ip link add dummy0 mtu 10 type dummy ip link add macsec0 link dummy0 type macsec ip link show macsec0 Before: 11: macsec0@dummy0: <BROADCAST,MULTICAST,M-DOWN> mtu 4294967274 After: 11: macsec0@dummy0: <BROADCAST,MULTICAST,M-DOWN> mtu 0 Fixes: ("macsec: introduce IEEE 802.1AE driver") Signed-off-by:

Taehee Yoo <ap420073@gmail.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/macsec.c

+8 −4

Original line number	Diff line number	Diff line
		@@ -4002,11 +4002,11 @@ static int macsec_newlink(struct net net, struct net_device dev,
		struct netlink_ext_ack *extack)
		{
		struct macsec_dev *macsec = macsec_priv(dev);
		rx_handler_func_t *rx_handler;
		u8 icv_len = DEFAULT_ICV_LEN;
		struct net_device *real_dev;
		int err;
		int err, mtu;
		sci_t sci;
		u8 icv_len = DEFAULT_ICV_LEN;
		rx_handler_func_t *rx_handler;

		if (!tb[IFLA_LINK])
		return -EINVAL;
		@@ -4033,7 +4033,11 @@ static int macsec_newlink(struct net net, struct net_device dev,

		if (data && data[IFLA_MACSEC_ICV_LEN])
		icv_len = nla_get_u8(data[IFLA_MACSEC_ICV_LEN]);
		dev->mtu = real_dev->mtu - icv_len - macsec_extra_len(true);
		mtu = real_dev->mtu - icv_len - macsec_extra_len(true);
		if (mtu < 0)
		dev->mtu = 0;
		else
		dev->mtu = mtu;

		rx_handler = rtnl_dereference(real_dev->rx_handler);
		if (rx_handler && rx_handler != macsec_handle_frame)

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