Executive brief
A vulnerability in the Linux kernel's ibmveth network driver can cause network adapters on IBM Power systems to freeze. This occurs when the system attempts to process specific types of network traffic with a small Maximum Segment Size (MSS). If triggered, all network traffic to and from the affected system will stop until the adapter is manually reset, potentially leading to a complete service outage.
Technical details
A flaw exists in the ibmveth driver where physical adapters on Power systems do not support hardware segmentation offload (GSO/LSO) when the MSS is less than 224 bytes. When the hardware attempts to segment these small packets (where gso_segs > 1), the adapter enters a freeze state, resulting in a denial of service. The fix implements an 'ndo_features_check' callback to detect packets with an MSS below the 224-byte threshold and force software segmentation instead. This ensures the problematic hardware code path is bypassed while maintaining connectivity.
Affected products
- Linux Linux Kernel ibmveth driver
Timeline
- 2026-04-24: disclosed: Initial patch submission by IBM
- 2026-06-01: patched: Patch committed to stable tree
- 2026-06-03: advisory: CVE-2026-46273 published
References
- https://git.kernel.org/stable/c/1cdf5dbcec988d06f5f720bdf89e91073f77fa10
- https://git.kernel.org/stable/c/3af24f0c4c31f18a4a2d927990759194832bb6e9
- https://git.kernel.org/stable/c/82bc89fbb82d9396fb4eaee8720ea85e2e787957
- https://git.kernel.org/stable/c/86fc64584811d43c9ccd74447de58620189d8b77
- https://git.kernel.org/stable/c/9a5e984d7af910e46dcbed3ce77873e000a4f77d
- https://git.kernel.org/stable/c/c1f261863e65b508f37416dfbc5c5d911c9b9233
- https://git.kernel.org/stable/c/cc427d24ac6442ffdeafd157a63c7c5b73ed4de4