From e16e960d55a40d36bd7c2494cc005e757dc9a1ef Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 6 Aug 2026 10:38:57 +0000 Subject: [PATCH] ipvlan: inherit needed_headroom and needed_tailroom from phy_dev ipvlan devices inherit hard_header_len from phy_dev during ipvlan_init(), but leave needed_headroom and needed_tailroom set to 0. When the underlying phy_dev (or stacked lower device) requires extra headroom or tailroom for headers/trailers (e.g. macsec, ipsec, wireguard, tunnels, or veth with rx headroom), upper layers calculating packet headroom and tailroom fail to reserve sufficient space. This can result in reallocation overhead, skb headroom underflows, or KASAN slab-use-after-free crashes when dev_hard_header() / ipvlan_hard_header() prepends header data or when lower devices append tailroom. Fix this by: 1. Inheriting needed_headroom and needed_tailroom from phy_dev in ipvlan_init(). 2. Propagating needed_headroom and needed_tailroom updates to attached ipvlans in ipvlan_device_event() when receiving NETDEV_FEAT_CHANGE events. Fixes: 2ad7bf363841 ("ipvlan: Initial check-in of the IPVLAN driver.") Reported-by: syzbot+1f9fd0f4b601cf88d6e6@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a720a21.40259c87.584f4.04bb.GAE@google.com/T/#u Reported-by: Tangxin Xie Closes: https://lore.kernel.org/netdev/CANn89i+1EW-sFNK8xoq98gMbPCeLS7e=+rs9gHfLg5Wj+4x0sw@mail.gmail.com/T/#mcc6307f115e500df23ea2980d5669fe95f20b6b4 Signed-off-by: Eric Dumazet Reviewed-by: Hangbin Liu Link: https://patch.msgid.link/20260806103857.115541-1-edumazet@google.com Signed-off-by: Jakub Kicinski --- drivers/net/ipvlan/ipvlan_main.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/ipvlan/ipvlan_main.c b/drivers/net/ipvlan/ipvlan_main.c index ed46439a9f4e..92d3d340281f 100644 --- a/drivers/net/ipvlan/ipvlan_main.c +++ b/drivers/net/ipvlan/ipvlan_main.c @@ -146,6 +146,8 @@ static int ipvlan_init(struct net_device *dev) dev->lltx = true; netif_inherit_tso_max(dev, phy_dev); dev->hard_header_len = phy_dev->hard_header_len; + dev->needed_headroom = phy_dev->needed_headroom; + dev->needed_tailroom = phy_dev->needed_tailroom; netdev_lockdep_set_classes(dev); @@ -773,6 +775,8 @@ static int ipvlan_device_event(struct notifier_block *unused, case NETDEV_FEAT_CHANGE: list_for_each_entry(ipvlan, &port->ipvlans, pnode) { netif_inherit_tso_max(ipvlan->dev, dev); + ipvlan->dev->needed_headroom = dev->needed_headroom; + ipvlan->dev->needed_tailroom = dev->needed_tailroom; netdev_update_features(ipvlan->dev); } break; -- 2.47.3