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Commit a62aa84f authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
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macvlan: enforce a consistent minimal mtu 



commit b64085b00044bdf3cd1c9825e9ef5b2e0feae91a upstream.

macvlan should enforce a minimal mtu of 68, even at link creation.

This patch avoids the current behavior (which could lead to crashes
in ipv6 stack if the link is brought up)

$ ip link add macvlan1 link eno1 mtu 8 type macvlan  # This should fail !
$ ip link sh dev macvlan1
5: macvlan1@eno1: <BROADCAST,MULTICAST> mtu 8 qdisc noop
    state DOWN mode DEFAULT group default qlen 1000
    link/ether 02:47:6c:24:74:82 brd ff:ff:ff:ff:ff:ff
$ ip link set macvlan1 mtu 67
Error: mtu less than device minimum.
$ ip link set macvlan1 mtu 68
$ ip link set macvlan1 mtu 8
Error: mtu less than device minimum.

Fixes: 91572088 ("net: use core MTU range checking in core net infra")
Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4f348b60

drivers/net/macvlan.c

+1 −1
Original line number Diff line number Diff line
@@ -1166,7 +1166,7 @@ void macvlan_common_setup(struct net_device *dev) 
{

	ether_setup(dev);



	dev->min_mtu		= 0;

	/* ether_setup() has set dev->min_mtu to ETH_MIN_MTU. */

	dev->max_mtu		= ETH_MAX_MTU;

	dev->priv_flags	       &= ~IFF_TX_SKB_SHARING;

	netif_keep_dst(dev);