CVE-2026-45837 bpf: Fix use-after-free in arena_vm_close on fork

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix use-after-free in arenavmclose on fork arenavmopen only bumps vml-mmapcount but never registers the child VMA in arena-vmalist. The vml-vma always points at the parent VMA, so after parent munmap the pointer dangles. If...