Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: macvlan: inherit needed_headroom and needed_tailroom from lowerdev macvlan devices inherit hard_header_len from lowerdev during macvlan_init(), but leave needed_headroom and needed_tailroom set to 0. When the underlying lowerdev 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() / macvlan_hard_header() prepends header data or when lower devices append tailroom. Fix this by: 1. Inheriting needed_headroom and needed_tailroom from lowerdev in macvlan_init(). 2. Propagating needed_headroom and needed_tailroom updates to attached macvlans in macvlan_device_event() when receiving NETDEV_FEAT_CHANGE events.

Affected versions

Linux: b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before c2ef3f134b069c54b9cc95cce1a16c38c4939336 (git); b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before 7b0eb3e0f363ca79a3af9efd2e87c6258f11da2b (git); b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before 8cd90e850e434577bf6774778657d26d6995e53f (git); b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before 28afc87bd8da0b3348bbbd834c8a89e83712cf5e (git); b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before 8f6a05dbac05725e0786701eb04778c5bdbe4eaa (git); b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before 96fa90b74385b7f2b0d97251dd43d5ee6ca44668 (git); b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before bc9a00fb78e32bccc39d763bfd13a450705bac5d (git); b863ceb7ddcea8c55fcf1d7b2ac591d50aa7ed53 through before cef51860becd9700217c81732ca1eb1ea6ed6fe1 (git); 2.6.23 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.