CVE-2026-31495

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

netfilter: ctnetlink: use netlink policy range checks

Replace manual range and mask validations with netlink policy annotations in ctnetlink code paths, so that the netlink core rejects invalid values early and can generate extack errors.

• CTAPROTOINFOTCPSTATE: reject values > TCPCONNTRACKSYNSENT2 at policy level, removing the manual >= TCPCONNTRACKMAX check.
• CTAPROTOINFOTCPWSCALEORIGINAL/REPLY: reject values > TCPMAXWSCALE (14). The normal TCP option parsing path already clamps to this value, but the ctnetlink path accepted 0-255, causing undefined behavior when used as a u32 shift count.
• CTAFILTERORIGFLAGS/REPLYFLAGS: use NLAPOLICYMASK with CTAFILTERF_ALL, removing the manual mask checks.
• CTAEXPECTFLAGS: use NLAPOLICYMASK with NFCTEXPECT_MASK, adding a new mask define grouping all valid expect flags.

Extracted from a broader nf-next patch by Florian Westphal, scoped to ctnetlink for the fixes tree.