PT-2026-54796 · Linux · Linux

Publicado 2026-07-01 · Atualizado 2026-07-01 · CVE-2026-53328

NVD

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

sched ext: Don't warn on NULL cgrp moving from in scx cgroup move task()

A WARN fires when systemd's user manager writes "+cpu +memory +pids" to its own subtree control while a sched ext scheduler is loaded:

WARNING: at kernel/sched/ext.c:3227 scx cgroup move task+0xa8/0xb0 scx cgroup move task+0xa8/0xb0 sched move task+0x134/0x290 cpu cgroup attach+0x39/0x70 cgroup migrate execute+0x37d/0x450 cgroup update dfl csses+0x1e3/0x270 cgroup subtree control write+0x3e7/0x440

scx cgroup can attach() arms cgrp moving from only when a task's cpu cgroup changes. It can still be NULL when scx cgroup move task() runs, through this sequence:

Step Result

---

1. cpu enabled on cgroup G cpu css = A
2. cpu toggled off then on for G A killed, B created (same cgroup)
3. an exiting task keeps A alive migration skips it, A now stale
4. +memory migrates G stale A vs current B pulls cpu in
5. cpu attach runs for all tasks hits a live, cpu-unchanged task
6. scx cgroup move task() on it cgrp moving from NULL -> WARN

The mismatch is that scx cgroup can attach() keys on cgroup identity while migration drives the move on css identity, so a NULL cgrp moving from here is a legitimate css-only migration, not a missing prep.

The call is already gated on cgrp moving from, so just drop the warning. ops.cgroup prep move() and ops.cgroup move() stay paired.

Identificadores relacionados

CVE-2026-53328

Produtos afetados

Linux

Referências · 5

• https://git.kernel.org/stable/c/02e545c4297a26dbbc41df81b831e7f605bcd306 · Nota
• https://git.kernel.org/stable/c/bc75f5951fac4e49d175c4433fc08fb1ec01172f · Nota
• https://nvd.nist.gov/vuln/detail/CVE-2026-53328 · Nota de Segurança
• https://git.kernel.org/stable/c/cdff2eb97be147d2ce52ac1327841068781f25dc · Nota
• https://git.kernel.org/stable/c/0ffcad63b19a1cadb475c9f405a93607fdcd0d7c · Nota