Red Hat Security Advisory 2017-0387-01 - The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements. Security Fix: Linux kernel built with the Kernel-based Virtual Machine support is vulnerable to a null pointer dereference flaw. It could occur on x86 platform, when emulating an undefined instruction. An attacker could use this flaw to crash the host kernel resulting in DoS.
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Red Hat Security Advisory
Synopsis: Important: kernel-rt security and bug fix update
Advisory ID: RHSA-2017:0387-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2017-0387.html
Issue date: 2017-03-02
CVE Names: CVE-2016-8630 CVE-2016-8655 CVE-2016-9083
CVE-2016-9084
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1. Summary:
An update for kernel-rt is now available for Red Hat Enterprise Linux 7.
Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.
2. Relevant releases/architectures:
Red Hat Enterprise Linux Realtime (v. 7) - noarch, x86_64
Red Hat Enterprise Linux for Real Time for NFV (v. 7) - noarch, x86_64
3. Description:
The kernel-rt packages provide the Real Time Linux Kernel, which enables
fine-tuning for systems with extremely high determinism requirements.
Security Fix(es):
* Linux kernel built with the Kernel-based Virtual Machine (CONFIG_KVM)
support is vulnerable to a null pointer dereference flaw. It could occur on
x86 platform, when emulating an undefined instruction. An attacker could
use this flaw to crash the host kernel resulting in DoS. (CVE-2016-8630,
Important)
* A race condition issue leading to a use-after-free flaw was found in the
way the raw packet sockets implementation in the Linux kernel networking
subsystem handled synchronization while creating the TPACKET_V3 ring
buffer. A local user able to open a raw packet socket (requires the
CAP_NET_RAW capability) could use this flaw to elevate their privileges on
the system. (CVE-2016-8655, Important)
* A flaw was discovered in the Linux kernel's implementation of VFIO. An
attacker issuing an ioctl can create a situation where memory is corrupted
and modify memory outside of the expected area. This may overwrite kernel
memory and subvert kernel execution. (CVE-2016-9083, Important)
* The use of a kzalloc with an integer multiplication allowed an integer
overflow condition to be reached in vfio_pci_intrs.c. This combined with
CVE-2016-9083 may allow an attacker to craft an attack and use unallocated
memory, potentially crashing the machine. (CVE-2016-9084, Moderate)
Red Hat would like to thank Philip Pettersson for reporting CVE-2016-8655.
Bug Fix(es):
* Previously, the asynchronous page fault woke code references spinlocks,
which were actually sleeping locks in the RT kernel. Because of this, when
the code was executed from the exception context, a bug warning appeared on
the console. With this update, the regular wait queue and spinlock code in
this area has been modified to use simple-wait-queue and raw-spinlocks.
This code change enables the asynchronous page fault code to run in a
non-preemptable state without bug warnings. (BZ#1418035)
4. Solution:
For details on how to apply this update, which includes the changes
described in this advisory, refer to:
https://access.redhat.com/articles/11258
The system must be rebooted for this update to take effect.
5. Bugs fixed (https://bugzilla.redhat.com/):
1389258 - CVE-2016-9083 kernel: State machine confusion bug in vfio driver leading to memory corruption
1389259 - CVE-2016-9084 kernel: Integer overflow when using kzalloc in vfio driver
1393350 - CVE-2016-8630 kernel: kvm: x86: NULL pointer dereference during instruction decode
1400019 - CVE-2016-8655 kernel: Race condition in packet_set_ring leads to use after free
1415172 - kernel-rt: update to the RHEL7.3.z batch#3 source tree [rt-7.3.z]
6. Package List:
Red Hat Enterprise Linux for Real Time for NFV (v. 7):
Source:
kernel-rt-3.10.0-514.10.2.rt56.435.el7.src.rpm
noarch:
kernel-rt-doc-3.10.0-514.10.2.rt56.435.el7.noarch.rpm
x86_64:
kernel-rt-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-devel-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-kvm-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-kvm-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-devel-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-kvm-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-kvm-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-devel-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-kvm-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-kvm-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
Red Hat Enterprise Linux Realtime (v. 7):
Source:
kernel-rt-3.10.0-514.10.2.rt56.435.el7.src.rpm
noarch:
kernel-rt-doc-3.10.0-514.10.2.rt56.435.el7.noarch.rpm
x86_64:
kernel-rt-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debug-devel-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-debuginfo-common-x86_64-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-devel-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-debuginfo-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
kernel-rt-trace-devel-3.10.0-514.10.2.rt56.435.el7.x86_64.rpm
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
https://access.redhat.com/security/team/key/
7. References:
https://access.redhat.com/security/cve/CVE-2016-8630
https://access.redhat.com/security/cve/CVE-2016-8655
https://access.redhat.com/security/cve/CVE-2016-9083
https://access.redhat.com/security/cve/CVE-2016-9084
https://access.redhat.com/security/updates/classification/#important
8. Contact:
The Red Hat security contact is <secalert@redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2017 Red Hat, Inc.
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