CVE-2026-72010

About vulnerability

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

cgroup/cpuset: rebind mm mempolicy to effective_mems, not mems_allowed

Creating a child cpuset where cpuset.mems is never set leads to a div/0 when a VMA mempolicy with MPOL_F_RELATIVE_NODES rebinds in response to a CPU hotplug event.

Reproduction steps:

1. Create a cgroup w/ cpuset controls (do not set cpuset.mems)
2. Move the task into the child cpuset
3. Create a VMA mempolicy for that task with MPOL_F_RELATIVE_NODES
4. unplug and hotplug a cpu echo 0 > /sys/devices/system/cpu/cpu1/online echo 1 > /sys/devices/system/cpu/cpu1/online
5. mempolicy rebind does a div/0 in mpol_relative_nodemask on the call to __nodes_fold()

The cpuset code passes (cs->mems_allowed) which is not guaranteed to have nodes to the rebind routine. Use cs->effective_mems instead, which is guaranteed to have a non-empty nodemask once we reach that code path.

[ david: add a comment, slightly rephrase description ]

Affected product:

AlmaLinux 9.2 ESU , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , Debian 10 ELS , Debian 11 ELS , TuxCare 9.6 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

kernel @ 5.14.0 (+9 more)

Live-patch status from KernelCare for each operating system.