title: Kernel: refcount leak in ctnetlink_create_conntrack()
description: A memory leak problem was found in ctnetlink_create_conntrack in net/netfilter/nf_conntrack_netlink.c in the Linux Kernel. This issue may allow a local attacker with CAP_NET_ADMIN privileges to cause a denial of service (DoS) attack due to a refcount overflow.
problem types: Missing Release of Memory after Effective Lifetime
affected:
{
product: Kernel
vendor: n/a
versions:
version: 6.3-rc1, status: unaffected
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:4.18.0-305.125.1.el8_4, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/o:redhat:rhel_e4s:8.4::baseos, cpe:/o:redhat:rhel_aus:8.4::baseos, cpe:/o:redhat:rhel_tus:8.4::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.4 Telecommunications Update Service
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel-rt
defaultStatus: affected
versions:
version: 0:4.18.0-305.125.1.rt7.201.el8_4, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_tus:8.4::realtime, cpe:/a:redhat:rhel_tus:8.4::nfv]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.4 Telecommunications Update Service
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:4.18.0-305.125.1.el8_4, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/o:redhat:rhel_e4s:8.4::baseos, cpe:/o:redhat:rhel_aus:8.4::baseos, cpe:/o:redhat:rhel_tus:8.4::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:4.18.0-305.125.1.el8_4, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/o:redhat:rhel_e4s:8.4::baseos, cpe:/o:redhat:rhel_aus:8.4::baseos, cpe:/o:redhat:rhel_tus:8.4::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.6 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:4.18.0-372.95.1.el8_6, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/o:redhat:enterprise_linux:8::hypervisor, cpe:/o:redhat:rhel_eus:8.6::baseos, cpe:/a:redhat:rhel_eus:8.6::crb]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.8 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:4.18.0-477.51.1.el8_8, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:8.8::crb, cpe:/o:redhat:rhel_eus:8.8::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9.0 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:5.14.0-70.93.2.el9_0, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:9.0::appstream, cpe:/o:redhat:rhel_eus:9.0::baseos, cpe:/a:redhat:rhel_eus:9.0::crb]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9.0 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel-rt
defaultStatus: affected
versions:
version: 0:5.14.0-70.93.1.rt21.165.el9_0, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:9.0::nfv, cpe:/a:redhat:rhel_eus:9.0::realtime]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9.2 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:5.14.0-284.52.1.el9_2, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:9.2::appstream, cpe:/a:redhat:rhel_eus:9.2::crb, cpe:/o:redhat:rhel_eus:9.2::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9.2 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel-rt
defaultStatus: affected
versions:
version: 0:5.14.0-284.52.1.rt14.337.el9_2, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:9.2::nfv, cpe:/a:redhat:rhel_eus:9.2::realtime]
}
{
vendor: Red Hat
product: Red Hat Virtualization 4 for Red Hat Enterprise Linux 8
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: affected
versions:
version: 0:4.18.0-372.95.1.el8_6, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/o:redhat:enterprise_linux:8::hypervisor, cpe:/o:redhat:rhel_eus:8.6::baseos, cpe:/a:redhat:rhel_eus:8.6::crb]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 6
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: kernel
defaultStatus: unknown
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: unknown
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: unknown
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: unaffected
}
metrics:
other: [
content: {'value': 'Moderate', 'namespace': 'https://access.redhat.com/security/updates/classification/'}
type: Red Hat severity rating
]
workarounds: Triggering this issue requires the ability to create user/net namespaces.
On non-containerized deployments of Red Hat Enterprise Linux 8, you can disable user namespaces by setting user.max_user_namespaces to 0:
# echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf
# sysctl -p /etc/sysctl.d/userns.conf
On containerized deployments, such as Red Hat OpenShift Container Platform, do not use this mitigation as the functionality is needed to be enabled.
Alternatively, skip loading the affected netfilter module (i.e., nf_conntrack_netlink) onto the system until we have a fix available. This can be done by a blacklist mechanism which will ensure the driver is not loaded at boot time.
~~~
How do I blacklist a kernel module to prevent it from loading automatically?
https://access.redhat.com/solutions/41278
~~~
