CVE-2026-64576 nexthop: initialize extack in nh_res_bucket_migrate()

In the Linux kernel, the following vulnerability has been resolved: nexthop: initialize extack in nhresbucketmigrate nhresbucketmigrate passes an uninitialized netlinkextack to callnexthopresbucketnotifiers. When nhnotifierresbucketinfoinit fails e.g. the kzalloc returns -ENOMEM, the error is...