CyberRota Analysis
AI-GeneratedA vulnerability in the Linux kernel affects the cpuset functionality, specifically when creating a child cpuset without setting `cpuset.mems`. This can lead to a division by zero error during a memory policy rebind triggered by a CPU hotplug event, potentially causing system instability. System administrators and developers managing Linux environments with cpuset configurations should prioritize addressing this issue to prevent operational disruptions.
Original NVD Description
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 ]