Bug 2524431 (CVE-2026-74744) - CVE-2026-74744 kernel: ipvlan: inherit needed_headroom and needed_tailroom from phy_dev
Summary: CVE-2026-74744 kernel: ipvlan: inherit needed_headroom and needed_tailroom fr...
Keywords:
Status: NEW
Alias: CVE-2026-74744
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-26 14:51 UTC by OSIDB Bzimport
Modified: 2026-08-27 06:46 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2026-08-26 14:51:01 UTC
In the Linux kernel, the following vulnerability has been resolved:

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.


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