cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.18.57, 7.2.11
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus() With commit 2125c0034c5d ("cgroup/cpuset: Make cpuset hotplug processing synchronous"), the cpuset hotplug operation becomes synchronous. That commit also removes the code that handles race between cpuset_hotplug_work and cpu hotplug notifier with the assumption that race is now gone. Later commit 7a0aabd9ce69 ("cgroup/cpuset: Always use cpu_active_mask") updates the cpuset code to always use cpu_active_mask instead of cpu_online_mask in some places including guarantee_online_cpus() which is renamed to guarantee_active_cpus() in that commit. In the case of CPU offline operation, cpu_active_mask is updated first in sched_cpu_deactivate() to remove the offline CPU before cpuset_handle_hotplug() is called to update the effective_cpus of the affected cpusets. The cpu_online_mask is updated after that near the end of the offline operation to remove the offline CPU. As a result, the race comes back and the top cpuset may not have any active CPU leading to NULL pointer dereference during the race window when guarantee_active_cpus() is called after cpu_active_mask is updated to remove the CPU to be torn down but before cpuset_handle_hotplug() is able to properly update the effective_cpus of the top cpuset. Fix this by adding back the NULL cs check to avoid this problem.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- Linux Linux
From 7a0aabd9ce697fc581ec691b21f748050fbcf004 · fixed in 8d88d3221204fbb1b6dc2c0f2f2181fe49126639; From 7a0aabd9ce697fc581ec691b21f748050fbcf004 · fixed in a21c255159bfe0034740292e10d2e258feeeb10d; From 7a0aabd9ce697fc581ec691b21f748050fbcf004 · fixed in 23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2
- Linux Linux
6.16
- KernelLinux
From 6.16.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.2.11