CVE-2024-26803

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

net: veth: clear GRO when clearing XDP even when down

veth sets NETIF_F_GRO automatically when XDP is enabled,

because both features use the same NAPI machinery.

The logic to clear NETIF_F_GRO sits in veth_disable_xdp() which

is called both on ndo_stop and when XDP is turned off.

To avoid the flag from being cleared when the device is brought

down, the clearing is skipped when IFF_UP is not set.

Bringing the device down should indeed not modify its features.

Unfortunately, this means that clearing is also skipped when

XDP is disabled _while_ the device is down. And there's nothing

on the open path to bring the device features back into sync.

IOW if user enables XDP, disables it and then brings the device

up we'll end up with a stray GRO flag set but no NAPI instances.

We don't depend on the GRO flag on the datapath, so the datapath

won't crash. We will crash (or hang), however, next time features

are sync'ed (eith

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References