UBUNTU-CVE-2026-90313: High severity ubuntu/linux-hwe-edge vulnerability

In the Linux kernel, the following vulnerability has been resolved: bpf, cgroup: Fix invalid storage access after cgroupbpfattach failed A potential invalid storage access issue can occur after replacing a cgroup bpf prog. This occurs in the following scenario: 1. prog1 with storage is attached to a cgroup in multi-attach mode. 2. prog1 is replaced with prog2 using BPFFREPLACE in multi-attach mode, but fails midway (e.g. in bpftrampolinelinkcgroupshim or updateeffectiveprogs). 3. A new prog3 is attached to the cgroup in multi-attach mode. The reason is that cgroupbpfattach overwrites pl->storage with the new storage prior to attachment completion. When attachment fails midway, the cleanup path calls bpfcgroupstoragesfree(newstorage) to free the newly allocated storage, but fails to restore pl->storage back to oldstorage. Consequently, the still-active prog1 holds invalid or dangling storage pointers, leading to an invalid memory access when prog1 executes and calls bpfgetlocalstorage. Additionally, original pl->flags and cgrp->bpf.flags[atype] are left unrestored. Fix this by saving oldplflags, oldstorage, and oldflags prior to the update, and properly restoring all of them in the cleanup path on error.