From: Eric Dumazet edumazet@google.com
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: 91572088e3fd ("net: use core MTU range checking in core net infra") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/macvlan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/macvlan.c +++ b/drivers/net/macvlan.c @@ -1176,7 +1176,7 @@ void macvlan_common_setup(struct net_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);