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AUSCERT External Security Bulletin Redistribution
Important: kernel-rt security and bug fix update
29 June 2017
AusCERT Security Bulletin Summary
Publisher: Red Hat
Operating System: Red Hat Enterprise Linux Server 6
Impact/Access: Root Compromise -- Existing Account
Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2017-1000364 CVE-2017-7895 CVE-2017-7645
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Red Hat Security Advisory
Synopsis: Important: kernel-rt security and bug fix update
Advisory ID: RHSA-2017:1647-01
Product: Red Hat Enterprise MRG for RHEL-6
Advisory URL: https://access.redhat.com/errata/RHSA-2017:1647
Issue date: 2017-06-28
CVE Names: CVE-2017-1000364 CVE-2017-6214 CVE-2017-7645
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.
2. Relevant releases/architectures:
MRG Realtime for RHEL 6 Server v.2 - noarch, x86_64
The kernel-rt packages provide the Real Time Linux Kernel, which enables
fine-tuning for systems with extremely high determinism requirements.
* A flaw was found in the way memory was being allocated on the stack for
user space binaries. If heap (or different memory region) and stack memory
regions were adjacent to each other, an attacker could use this flaw to
jump over the stack guard gap, cause controlled memory corruption on
process stack or the adjacent memory region, and thus increase their
privileges on the system. This is a kernel-side mitigation which increases
the stack guard gap size from one page to 1 MiB to make successful
exploitation of this issue more difficult. (CVE-2017-1000364, Important)
* The NFS2/3 RPC client could send long arguments to the NFS server. These
encoded arguments are stored in an array of memory pages, and accessed
using pointer variables. Arbitrarily long arguments could make these
pointers point outside the array and cause an out-of-bounds memory access.
A remote user or program could use this flaw to crash the kernel, resulting
in denial of service. (CVE-2017-7645, Important)
* The NFSv2 and NFSv3 server implementations in the Linux kernel through
4.10.13 lacked certain checks for the end of a buffer. A remote attacker
could trigger a pointer-arithmetic error or possibly cause other
unspecified impacts using crafted requests related to fs/nfsd/nfs3xdr.c and
fs/nfsd/nfsxdr.c. (CVE-2017-7895, Important)
* A flaw was found in the Linux kernel's handling of packets with the URG
flag. Applications using the splice() and tcp_splice_read() functionality
could allow a remote attacker to force the kernel to enter a condition in
which it could loop indefinitely. (CVE-2017-6214, Moderate)
Red Hat would like to thank Qualys Research Labs for reporting
CVE-2017-1000364 and Ari Kauppi for reporting CVE-2017-7895.
* kernel-rt packages have been upgraded to the 3.10.0-514 source tree,
which provides a number of bug fixes 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.
5. Bugs fixed (https://bugzilla.redhat.com/):
1426542 - CVE-2017-6214 kernel: ipv4/tcp: Infinite loop in tcp_splice_read()
1443615 - CVE-2017-7645 kernel: nfsd: Incorrect handling of long RPC replies
1446103 - CVE-2017-7895 kernel: NFSv3 server does not properly handle payload bounds checking of WRITE requests
1452745 - update the MRG 2.5.z 3.10 kernel-rt sources
1452769 - HPE iLO remote console video goes blank after updating to kernel-rt-3.10.0-514.rt56.210.el6rt
1461333 - CVE-2017-1000364 kernel: heap/stack gap jumping via unbounded stack allocations
6. Package List:
MRG Realtime for RHEL 6 Server v.2:
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
The Red Hat security contact is <email@example.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2017 Red Hat, Inc.
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