title: Kernel: blkio memory leakage due to blkcg and some blkgs are not freed after they are made offline.
description: A flaw was found in the blkgs destruction path in block/blk-cgroup.c in the Linux kernel, leading to a cgroup blkio memory leakage problem. When a cgroup is being destroyed, cgroup_rstat_flush() is only called at css_release_work_fn(), which is called when the blkcg reference count reaches 0. This circular dependency will prevent blkcg and some blkgs from being freed after they are made offline. This issue may allow an attacker with a local access to cause system instability, such as an out of memory error.
problem types: Transmission of Private Resources into a New Sphere ('Resource Leak')
affected:
{
product: kernel
vendor: n/a
defaultStatus: affected
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:4.18.0-513.5.1.el8_9, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:enterprise_linux:8::crb, cpe:/o:redhat:enterprise_linux:8::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 6
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: unaffected
cpes: cpe:/o:redhat:enterprise_linux:6
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 7
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: unaffected
cpes: cpe:/o:redhat:enterprise_linux:7
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 7
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel-rt
defaultStatus: unaffected
cpes: cpe:/o:redhat:enterprise_linux:7
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel-rt
defaultStatus: affected
cpes: cpe:/o:redhat:enterprise_linux:8
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
cpes: cpe:/o:redhat:enterprise_linux:9
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel-rt
defaultStatus: affected
cpes: cpe:/o:redhat:enterprise_linux:9
}
{
product: Fedora
vendor: Fedora
collectionURL: https://packages.fedoraproject.org/
packageName: kernel
defaultStatus: affected
}
metrics:
other: [
content: {'value': 'Moderate', 'namespace': 'https://access.redhat.com/security/updates/classification/'}
type: Red Hat severity rating
]
workarounds: This flaw can be mitigated with the possible workaround identified below:
- systemd.unified_cgroup_hierarchy=1
or
- cgroup_disable=blkio