Security Advisory Important: kernel-rt security and bug fix update

Advisory: RHSA-2017:0932-1
Type: Security Advisory
Severity: Important
Issued on: 2017-04-12
Last updated on: 2017-04-12
Affected Products: Red Hat Enterprise MRG v2 for Red Hat Enterprise Linux (version 6)
CVEs ( CVE-2016-8650


An update for kernel-rt is now available for Red Hat Enterprise MRG 2.

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.

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 use-after-free flaw was found in the way the Linux kernel's Datagram
Congestion Control Protocol (DCCP) implementation freed SKB (socket buffer)
resources for a DCCP_PKT_REQUEST packet when the IPV6_RECVPKTINFO option is set
on the socket. A local, unprivileged user could use this flaw to alter the
kernel memory, allowing them to escalate their privileges on the system.
(CVE-2017-6074, 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; Andrey
Konovalov (Google) for reporting CVE-2017-6074; and Ralf Spenneberg for
reporting CVE-2016-8650. The CVE-2017-2618 issue was discovered by Paul Moore
(Red Hat Engineering).

Bug Fix(es):

* The kernel-rt packages have been upgraded to version 3.10.0-514.rt56.219,
which provides a number of bug fix updates over the previous version.


For details on how to apply this update, which includes the changes described in
this advisory, refer to:

The system must be rebooted for this update to take effect.

Updated packages

Red Hat Enterprise MRG v2 for Red Hat Enterprise Linux (version 6)

File outdated by:  RHSA-2017:1297
    MD5: 0de29b82bbdc20115878b95e9c0c1f23
SHA-256: c95df7676e85f35fae36e3015f35791de885c6d5e1d7fd20d9e06baf414f2fdf
File outdated by:  RHSA-2017:1297
    MD5: a9b2cfbe55681c1a16f8a7f5fa2fb681
SHA-256: 916c0c7c4b9a2c9a15794663f5f4d3edc5f631f6c367af13bd384b9faadbeead
File outdated by:  RHSA-2017:1297
    MD5: 887fd81a7b319aa1fa6a4e3ba48fc9c2
SHA-256: 14ca5854add626601d1d307fd0c008527d14907c6ec0408f22e9843fc7f732f6
File outdated by:  RHSA-2017:1297
    MD5: d0fcf5f71161521f7b2aa458fc541a09
SHA-256: ffaf9639c31c05c34595d9500150f6cb4739207b07f666aa7c6afe1a239871f2
File outdated by:  RHSA-2017:1297
    MD5: e58134d33927a75ef98fbb0f6d4ed626
SHA-256: 852f4e88b909ea7bfe589ea38b8d3fe3c61bc196101ef20415d2f024f7419ab7
File outdated by:  RHSA-2017:1297
    MD5: 7f759dd93ee782fd7b1ac26d4e7adfe6
SHA-256: 77903ffd4fe1e79cde1a4443a32fd4f6217be62ce9eff22dc1c43c122acc0696
File outdated by:  RHSA-2017:1297
    MD5: b27e0d43209dc41b4b3d9f48dc74dfc2
SHA-256: 573550a0a7e493c9e83fe8efd26c7d69147c5fbdaf469b41781f0013a3247fd6
File outdated by:  RHSA-2017:1297
    MD5: 5ad4517c9ec688887dc48e0aec2a9ba3
SHA-256: 716425ea1d23ecc0bc3d96831f8203b5a62459ae672e378f35ed51f46b24d9c2
File outdated by:  RHSA-2017:1297
    MD5: e2fa0d0b91c836c386b84c22670438d7
SHA-256: 517c293af0fe53ef5d3053b4d2041954e1188e224ad0ae29af1a073d0abd897f
File outdated by:  RHSA-2017:1297
    MD5: 6f2fbe5c1ec78dfbe21c6a74b70f07e5
SHA-256: e4082d03e4e4cdd69ec63e9e0427187aec34bffdefb0162af3401a2dcd845a86
File outdated by:  RHSA-2017:1297
    MD5: ba504056dd36d17693178dbe57f422dd
SHA-256: 735d883052ed03dcf4e74da0f440aa185ca35fc64d9fde6eab5f7ba453cf4c77
File outdated by:  RHSA-2017:1297
    MD5: a48ea409ab8ae8a2c0d0b535eebe9427
SHA-256: fb5766257319f9ae2c22e6b2a526a714bcfdf319095e0d5344a43fcfedef8306
File outdated by:  RHSA-2017:1297
    MD5: 1ebc119db29645b60b469ed774c3590e
SHA-256: aad0964e63328813f775791495d573a45cdcf41a94583a70e5267b9781229f65
File outdated by:  RHSA-2017:1297
    MD5: ebbca287ac0ec51e63ea17fb04d812e0
SHA-256: 5ee65a9b960171b4944b130e401a563217e8f364ea316ff600a0bf63224a040c
File outdated by:  RHSA-2017:1297
    MD5: 96e1d2e4758cde469547f621b2454a4b
SHA-256: 8e34df15a7865b9e4558ecd4e467578ed778ade6da348da6408b24f4881d8c91
File outdated by:  RHSA-2017:1297
    MD5: 292fbba51c1aee7f88330f4c69ef39fb
SHA-256: 3825d49a021e12d80e32277bd7faed73bc6f1e78a8d8d120599e5216a4284987
(The unlinked packages above are only available from the Red Hat Network)

Bugs fixed (see bugzilla for more information)

1395187 - CVE-2016-8650 kernel: Null pointer dereference via keyctl
1402013 - CVE-2016-9793 kernel: Signed overflow for SO_{SND|RCV}BUFFORCE
1419916 - CVE-2017-2618 kernel: Off-by-one error in selinux_setprocattr (/proc/self/attr/fscreate)
1423071 - CVE-2017-6074 kernel: use after free in dccp protocol
1428319 - CVE-2017-2636 kernel: Race condition access to n_hdlc.tbuf causes double free in n_hdlc_release()
1429613 - update the MRG 2.5.z 3.10 kernel-rt sources


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