CVE-2026-31531 ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop()

In the Linux kernel, the following vulnerability has been resolved: ipv4: nexthop: allocate skb dynamically in rtmgetnexthop When querying a nexthop object via RTMGETNEXTHOP, the kernel currently allocates a fixed-size skb using NLMSGGOODSIZE. While sufficient for single nexthops and small...