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Red Hat Security Advisory
Synopsis: Important: kernel-rt security and bug fix update
Advisory ID: RHSA-2017:1616-01
Product: Red Hat Enterprise Linux
Advisory URL: https://access.redhat.com/errata/RHSA-2017:1616
Issue date: 2017-06-28
CVE Names: CVE-2017-1000364 CVE-2017-2583 CVE-2017-6214
CVE-2017-7477 CVE-2017-7645 CVE-2017-7895
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
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)
* A flaw was found in the way Linux kernel allocates heap memory to build
the scattergather list from a fragment list(skb_shinfo(skb)->frag_list) in
the socket buffer(skb_buff). The heap overflow occurred if 'MAX_SKB_FRAGS +
1' parameter and 'NETIF_F_FRAGLIST' feature are both used together.
remote user or process could use this flaw to potentially escalate their
privilege on a system. (CVE-2017-7477, 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)
* Linux kernel built with the Kernel-based Virtual Machine (CONFIG_KVM)
support was vulnerable to an incorrect segment selector(SS) value error.
The error could occur while loading values into the SS register in long
mode. A user or process inside a guest could use this flaw to crash the
guest, resulting in DoS or potentially escalate their privileges inside the
guest. (CVE-2017-2583, Moderate)
* 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; Ari Kauppi for reporting CVE-2017-7895; and Xiaohan Zhang
(Huawei Inc.) for reporting CVE-2017-2583.
* The kernel-rt packages have been upgraded to the 3.10.0-514.25.2 source
tree, which provides a number of bug fixes over the previous version.
* Previously, a local lock acquisition around the ip_send_unicast_reply()
function was incorrectly terminated. Consequently, a list corruption
occurred that led to a kernel panic. This update adds locking functions
around calls to ip_send_unicast_reply(). As a result, neither list
corruption nor kernel panic occur under the described circumstances.
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/):
1414735 - CVE-2017-2583 Kernel: Kvm: vmx/svm potential privilege escalation
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
1445207 - CVE-2017-7477 kernel: net: Heap overflow in skb_to_sgvec in macsec.c
1446103 - CVE-2017-7895 kernel: NFSv3 server does not properly handle payload
bounds checking of WRITE requests
1452742 - kernel-rt: update to the RHEL7.3.z batch#6 source tree
1455239 - net: add back the missing serialization in ip_send_unicast_reply()
1461333 - CVE-2017-1000364 kernel: heap/stack gap jumping via unbounded stack
6. Package List:
Red Hat Enterprise Linux for Real Time for NFV (v. 7):
Red Hat Enterprise Linux Realtime (v. 7):
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 <firstname.lastname@example.org>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2017 Red Hat, Inc.
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