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Category:   OS (Linux)  >   Linux Kernel Vendors:
(Red Hat Issues Fix) Linux Kernel NFSv4 Server Input Validation Flaw in pNFS LAYOUTGET Command Lets Remote Users Cause the Target Service to Crash
SecurityTracker Alert ID:  1039273
SecurityTracker URL:
CVE Reference:   CVE-2017-8797   (Links to External Site)
Date:  Sep 6 2017
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): RHEL 6
Description:   A vulnerability was reported in the Linux kernel NFSv4 Server. A remote user can cause the target service to crash.

A remote user on a system within the target mount's host address mask range can send a specially crafted NFSv4 pNFS LAYOUTGET command via UDP to trigger an input validation and array deference error and cause the target service to crash.

Systems compiled with CONFIG_NFSD_PNFS enabled are affected.

Jani Tuovila from Synopsys Ltd reported this vulnerability.

Impact:   A remote user can cause the target service to crash.
Solution:   Red Hat has issued a fix.

The Red Hat advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Access control error, Input validation error

Message History:   This archive entry is a follow-up to the message listed below.
Jun 27 2017 Linux Kernel NFSv4 Server Input Validation Flaw in pNFS LAYOUTGET Command Lets Remote Users Cause the Target Service to Crash

 Source Message Contents

Subject:  [RHSA-2017:2669-01] Important: kernel-rt security and bug fix update

Hash: SHA1

                   Red Hat Security Advisory

Synopsis:          Important: kernel-rt security and bug fix update
Advisory ID:       RHSA-2017:2669-01
Product:           Red Hat Enterprise MRG for RHEL-6
Advisory URL:
Issue date:        2017-09-06
CVE Names:         CVE-2015-8839 CVE-2016-10088 CVE-2016-7042 
                   CVE-2016-7097 CVE-2016-8645 CVE-2016-9576 
                   CVE-2016-9604 CVE-2016-9685 CVE-2016-9806 
                   CVE-2017-2671 CVE-2017-5970 CVE-2017-6001 
                   CVE-2017-6951 CVE-2017-7187 CVE-2017-7533 
                   CVE-2017-7889 CVE-2017-8797 CVE-2017-8890 
                   CVE-2017-9074 CVE-2017-9075 CVE-2017-9076 

1. Summary:

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

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):

* A race condition was found in the Linux kernel, present since v3.14-rc1
through v4.12. The race happens between threads of inotify_handle_event()
and vfs_rename() while running the rename operation against the same file.
As a result of the race the next slab data or the slab's free list pointer
can be corrupted with attacker-controlled data, which may lead to the
privilege escalation. (CVE-2017-7533, Important)

* It was found that the NFSv4 server in the Linux kernel did not properly
validate layout type when processing NFSv4 pNFS LAYOUTGET and GETDEVICEINFO
operands. A remote attacker could use this flaw to soft-lockup the system
and thus cause denial of service. (CVE-2017-8797, Important)

This update also fixes multiple Moderate and Low impact security issues:

CVE-2017-8797 CVE-2015-8839 CVE-2016-9576 CVE-2016-7042 CVE-2016-7097
CVE-2016-8645 CVE-2016-9576 CVE-2016-9806 CVE-2016-10088 CVE-2017-2671
CVE-2017-5970 CVE-2017-6001 CVE-2017-6951 CVE-2017-7187 CVE-2017-7889
CVE-2017-8890 CVE-2017-9074 CVE-2017-8890 CVE-2017-9075 CVE-2017-8890
CVE-2017-9076 CVE-2017-8890 CVE-2017-9077 CVE-2016-9604 CVE-2016-9685

Documentation for these issues are available from the Technical Notes
document linked to in the References section.

Red Hat would like to thank Leilei Lin (Alibaba Group), Fan Wu (The
University of Hong Kong), and Shixiong Zhao (The University of Hong Kong)
for reporting CVE-2017-7533 and Marco Grassi for reporting CVE-2016-8645.
The CVE-2016-7042 issue was discovered by Ondrej Kozina (Red Hat); the
CVE-2016-7097 issue was discovered by Andreas Gruenbacher (Red Hat) and Jan
Kara (SUSE); the CVE-2016-9604 issue was discovered by David Howells (Red
Hat); and the CVE-2016-9685 issue was discovered by Qian Cai (Red Hat).

4. Solution:

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 (

1323577 - CVE-2015-8839 kernel: ext4 filesystem page fault race condition with fallocate call.
1368938 - CVE-2016-7097 kernel: Setting a POSIX ACL via setxattr doesn't clear the setgid bit
1373966 - CVE-2016-7042 kernel: Stack corruption while reading /proc/keys when gcc stack protector is enabled
1389433 - CVE-2016-9604 kernel: security: The built-in keyrings for security tokens can be joined as a session and then modified by the root user
1393904 - CVE-2016-8645 kernel: a BUG() statement can be hit in net/ipv4/tcp_input.c
1396941 - CVE-2016-9685 kernel: Memory leaks in xfs_attr_list.c error paths
1401502 - CVE-2016-9806 kernel: netlink: double-free in netlink_dump
1403145 - CVE-2016-9576 kernel: Use after free in SCSI generic device interface
1412210 - CVE-2016-10088 kernel: Use after free in SCSI generic device interface (CVE-2016-9576 regression)
1421638 - CVE-2017-5970 kernel: ipv4: Invalid IP options could cause skb->dst drop
1422825 - CVE-2017-6001 kernel: Race condition between multiple sys_perf_event_open() calls
1433252 - CVE-2017-6951 kernel: NULL pointer dereference in keyring_search_aux function
1434327 - CVE-2017-7187 kernel: scsi: Stack-based buffer overflow in sg_ioctl function
1436649 - CVE-2017-2671 kernel: ping socket / AF_LLC connect() sin_family race
1444493 - CVE-2017-7889 kernel: mm subsystem does not properly enforce the CONFIG_STRICT_DEVMEM protection mechanism
1450972 - CVE-2017-8890 kernel: Double free in the inet_csk_clone_lock function in net/ipv4/inet_connection_sock.c
1452679 - CVE-2017-9074 kernel: net: IPv6 fragmentation implementation of nexthdr field may be associated with an invalid option
1452688 - CVE-2017-9076 kernel: net: IPv6 DCCP implementation mishandles inheritance
1452691 - CVE-2017-9075 kernel: net: sctp_v6_create_accept_sk function mishandles inheritance
1452744 - CVE-2017-9077 kernel: net: tcp_v6_syn_recv_sock function mishandles inheritance
1466329 - CVE-2017-8797 kernel: NFSv4 server does not properly validate layout type when processing NFSv4 pNFS LAYOUTGET operand
1468283 - CVE-2017-7533 kernel: a race between inotify_handle_event() and sys_rename()
1479016 - update the MRG 2.5.z 3.10 kernel-rt sources

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

7. References:

8. Contact:

The Red Hat security contact is <>. More contact
details at

Copyright 2017 Red Hat, Inc.
Version: GnuPG v1


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