CVE-2026-98853net: gso: limit recursive IP-in-IP segmentation

Official description

In the Linux kernel, the following vulnerability has been resolved: net: gso: limit recursive IP-in-IP segmentation IP-in-IP GSO can re-enter inet_gso_segment() or ipv6_gso_segment() for each nested IP header. encap_level tracks header bytes, not callback depth, so a deep chain can exhaust the kernel stack. Making inet_gso_segment() stackable introduced unbounded IPv4 nesting; IPIP GSO/TSO later made the path reachable. The IPv6 stackable path was introduced separately and uses the same guard. Count IPv4 and IPv6 GSO handler entries in skb_gso_cb, initialized once per top-level GSO operation and preserved across GRE/UDP context changes. Use the existing IP_TUNNEL_RECURSION_LIMIT for both handlers. The first five entries pass, and the sixth returns -EINVAL before dispatching another GSO callback.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/388604279da3d0698a151efa4fb6d852efa0de4a
• https://git.kernel.org/stable/c/c949646c900e879afce47df1b607fa320eb63bf2
• https://git.kernel.org/stable/c/006c8b834aed8b02bd8fb9fb05e9e7ead37d1763