Synopsis

Important: kernel-rt security and bug fix update

Type/Severity

Security Advisory: Important

Topic

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.

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):

• A race condition flaw was found in the N_HLDC Linux kernel driver when accessing n_hdlc.tbuf list that can lead to double free. A local, unprivileged user able to set the HDLC line discipline on the tty device could use this flaw to increase their privileges on the system. (CVE-2017-2636, Important)
  
• A flaw was found in the Linux kernel key management subsystem in which a local attacker could crash the kernel or corrupt the stack and additional memory (denial of service) by supplying a specially crafted RSA key. This flaw panics the machine during the verification of the RSA key. (CVE-2016-8650, Moderate)
  
• A flaw was found in the Linux kernel's implementation of setsockopt for the SO_{SND|RCV}BUFFORCE setsockopt() system call. Users with non-namespace CAP_NET_ADMIN are able to trigger this call and create a situation in which the sockets sendbuff data size could be negative. This could adversely affect memory allocations and create situations where the system could crash or cause memory corruption. (CVE-2016-9793, Moderate)
  
• A flaw was found in the Linux kernel's handling of clearing SELinux attributes on /proc/pid/attr files. An empty (null) write to this file can crash the system by causing the system to attempt to access unmapped kernel memory. (CVE-2017-2618, Moderate)
  

Red Hat would like to thank Alexander Popov for reporting CVE-2017-2636 and Ralf Spenneberg for reporting CVE-2016-8650. The CVE-2017-2618 issue was discovered by Paul Moore (Red Hat Engineering).

Bug Fix(es):

• Previously, a cgroups data structure was sometimes corrupted due to a race condition in the kernel-rt cgroups code. Consequently, several system tasks were blocked, and the operating system became unresponsive. This update adds a lock that prevents the race condition. As a result, the cgroups data structure no longer gets corrupted and the operating system no longer hangs under the described circumstances. (BZ#1420784)
  
• The kernel-rt packages have been upgraded to the 3.10.0-514.16.1 source tree, which provides a number of bug fixes over the previous version. (BZ#1430749)

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.

Affected Products

• Red Hat Enterprise Linux for Real Time 7 x86_64
• Red Hat Enterprise Linux for Real Time for NFV 7 x86_64

Fixes

• BZ - 1395187 - CVE-2016-8650 kernel: Null pointer dereference via keyctl
• BZ - 1402013 - CVE-2016-9793 kernel: Signed overflow for SO_{SND|RCV}BUFFORCE
• BZ - 1419916 - CVE-2017-2618 kernel: Off-by-one error in selinux_setprocattr (/proc/self/attr/fscreate)
• BZ - 1428319 - CVE-2017-2636 kernel: Race condition access to n_hdlc.tbuf causes double free in n_hdlc_release()
• BZ - 1430749 - kernel-rt: update to the RHEL7.3.z batch#4 source tree [RT-7.3.z]

CVEs

• CVE-2016-8650
• CVE-2016-9793
• CVE-2017-2618
• CVE-2017-2636

References

• https://access.redhat.com/security/updates/classification/#important

Red Hat Enterprise Linux for Real Time 7

SRPM
kernel-rt-3.10.0-514.16.1.rt56.437.el7.src.rpm	SHA-256: 9c60da2123867019f21ff8df984b553c972e89bad3e96045908e1f1adc48f968
x86_64
kernel-rt-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 2aba3c5689a347e0659abbb12a5320dc905081bf6797e88da8b02017df6a9fe9
kernel-rt-debug-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: ed65533d8223c0871a9684eae69af4484123df4acbbc0c00819c707210f9bb37
kernel-rt-debug-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: bf9d3b91a7aa14ce16036b3040b441ee11c3ee82f91e17a238ba0f1362ba2282
kernel-rt-debug-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 22ae04aec5121676e4989313b2a44d72f05b0c47a26dd866c4d8b58ab4370fc4
kernel-rt-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 95f964596fe68c99455ee580771c6d9092e709a4c99450d588b72acf1ea2c461
kernel-rt-debuginfo-common-x86_64-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 6f63d4d18ac05437db4f8a277af3df605ef1d459eca7d7b0bb749162135437f4
kernel-rt-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 30559fe3f107a57f8490ada6814f4676c63cad18f5c28dd1b0ebfe9a474d2ec6
kernel-rt-doc-3.10.0-514.16.1.rt56.437.el7.noarch.rpm	SHA-256: 67a8f32a74d7f3248cd6655270fcc7c306923eda0324dfbf98a81db31e49e041
kernel-rt-trace-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: fa66ad788766abe583887db52aad4c757f3bbdf5a2aa6ecdd44fedcede4414c0
kernel-rt-trace-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: f146b6c6fa4eb65defe711281c5a0e9a547cd9c73d66d51312d231daa178f16f
kernel-rt-trace-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 4ea5313b7e56dcbfc7eb7b9a4eb30336fc17b6b6f3ae9cf2f3ce566c5f2e5780

Red Hat Enterprise Linux for Real Time for NFV 7

SRPM
kernel-rt-3.10.0-514.16.1.rt56.437.el7.src.rpm	SHA-256: 9c60da2123867019f21ff8df984b553c972e89bad3e96045908e1f1adc48f968
x86_64
kernel-rt-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 2aba3c5689a347e0659abbb12a5320dc905081bf6797e88da8b02017df6a9fe9
kernel-rt-debug-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: ed65533d8223c0871a9684eae69af4484123df4acbbc0c00819c707210f9bb37
kernel-rt-debug-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: bf9d3b91a7aa14ce16036b3040b441ee11c3ee82f91e17a238ba0f1362ba2282
kernel-rt-debug-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 22ae04aec5121676e4989313b2a44d72f05b0c47a26dd866c4d8b58ab4370fc4
kernel-rt-debug-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 834ebe687817625b7f0dc4aefae1a1b766c2243fd17ffd707af156d8802ee195
kernel-rt-debug-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 7f2d03bf51d48092190fafea0db9c40b2b03036e1e4342ed5b96a0a2440716d8
kernel-rt-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 95f964596fe68c99455ee580771c6d9092e709a4c99450d588b72acf1ea2c461
kernel-rt-debuginfo-common-x86_64-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 6f63d4d18ac05437db4f8a277af3df605ef1d459eca7d7b0bb749162135437f4
kernel-rt-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 30559fe3f107a57f8490ada6814f4676c63cad18f5c28dd1b0ebfe9a474d2ec6
kernel-rt-doc-3.10.0-514.16.1.rt56.437.el7.noarch.rpm	SHA-256: 67a8f32a74d7f3248cd6655270fcc7c306923eda0324dfbf98a81db31e49e041
kernel-rt-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 49225dd2c3422d22b20635459bfa05487b35588d593eeda419db6375a2977b2a
kernel-rt-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 9aa1785754c7add31e062112bf86e523bd6820a14e3e950a17466b679df061e3
kernel-rt-trace-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: fa66ad788766abe583887db52aad4c757f3bbdf5a2aa6ecdd44fedcede4414c0
kernel-rt-trace-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: f146b6c6fa4eb65defe711281c5a0e9a547cd9c73d66d51312d231daa178f16f
kernel-rt-trace-devel-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 4ea5313b7e56dcbfc7eb7b9a4eb30336fc17b6b6f3ae9cf2f3ce566c5f2e5780
kernel-rt-trace-kvm-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: b211cb51e509e6894cf75d39a19f57474ec25dc78e6202cd333805f8377f929e
kernel-rt-trace-kvm-debuginfo-3.10.0-514.16.1.rt56.437.el7.x86_64.rpm	SHA-256: 1261340f78adca4c365de558476e0fc9227b5d2caa782f1b5765751e400cdd9b