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Category:   Application (Generic)  >   Red Hat Enterprise MRG Grid Vendors:   Red Hat
(Red Hat Issues Fix for Red Hat Enterprise MRG) Linux ping Use-After-Free Memory Error Lets Local Users Deny Service and Gain Elevated Privileges
SecurityTracker Alert ID:  1033191
SecurityTracker URL:
CVE Reference:   CVE-2015-3636   (Links to External Site)
Date:  Aug 6 2015
Impact:   Denial of service via local system, Execution of arbitrary code via local system, Root access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   A vulnerability was reported in Linux ping. A local user can cause denial of service conditions on the target system. A local user can obtain elevated privileges on the target system. Red Hat Enterprise MRG is affected.

A local user can make a SOCK_DGRAM socket system call for the IPPROTO_ICMP or IPPROTO_ICMPV6 protocols and then make a connect() system call after a disconnect to trigger a use-after-free in the ping_unhash() function to execute arbitrary code or cause the system to crash.

Impact:   A local user can cause the target system to crash.

A local user can obtain root privileges on the target system.

Solution:   Red Hat has issued a fix for Red Hat Enterprise MRG.

The Red Hat advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Access control error
Underlying OS:  Linux (Red Hat Enterprise)
Underlying OS Comments:  6

Message History:   This archive entry is a follow-up to the message listed below.
Aug 6 2015 Linux ping Use-After-Free Memory Error Lets Local Users Deny Service and Gain Elevated Privileges

 Source Message Contents

Subject:  [RHSA-2015:1564-01] Moderate: kernel-rt security, bug fix, and enhancement update

Hash: SHA1

                   Red Hat Security Advisory

Synopsis:          Moderate: kernel-rt security, bug fix, and enhancement update
Advisory ID:       RHSA-2015:1564-01
Product:           Red Hat Enterprise MRG for RHEL-6
Advisory URL:
Issue date:        2015-08-05
CVE Names:         CVE-2014-9715 CVE-2015-2922 CVE-2015-3636 

1. Summary:

Updated kernel-rt packages that fix three security issues, several bugs,
and add various enhancements are now available for Red Hat Enterprise MRG

Red Hat Product Security has rated this update as having Moderate security
impact. Common Vulnerability Scoring System (CVSS) base scores, which give
detailed severity ratings, are available for each vulnerability from the
CVE links 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 contain the Linux kernel, the core of any Linux
operating system.

* An integer overflow flaw was found in the way the Linux kernel's
netfilter connection tracking implementation loaded extensions. An attacker
on a local network could potentially send a sequence of specially crafted
packets that would initiate the loading of a large number of extensions,
causing the targeted system in that network to crash. (CVE-2014-9715,

* It was found that the Linux kernel's ping socket implementation did not
properly handle socket unhashing during spurious disconnects, which could
lead to a use-after-free flaw. On x86-64 architecture systems, a local user
able to create ping sockets could use this flaw to crash the system.
On non-x86-64 architecture systems, a local user able to create ping
sockets could use this flaw to escalate their privileges on the system.
(CVE-2015-3636, Moderate)

* It was found that the Linux kernel's TCP/IP protocol suite implementation
for IPv6 allowed the Hop Limit value to be set to a smaller value than the
default one. An attacker on a local network could use this flaw to prevent
systems on that network from sending or receiving network packets.
(CVE-2015-2922, Low)

Red Hat would like to thank Nathan Hoad for reporting the CVE-2014-9715

This update provides a build of the kernel-rt package for Red Hat
Enterprise MRG 2.5 that is layered on Red Hat Enterprise Linux 6, and fixes
the following issues:

* drbg: Add stdrng alias and increase priority
* seqiv / eseqiv / chainiv: Move IV seeding into init function
* ipv4: kABI fix for 0bbf87d backport
* ipv4: Convert ipv4.ip_local_port_range to be per netns
* libceph: tcp_nodelay support
* ipr: Increase default adapter init stage change timeout
* fix use-after-free bug in usb_hcd_unlink_urb()
* libceph: fix double __remove_osd() problem
* ext4: fix data corruption caused by unwritten and delayed extents
* sunrpc: Add missing support for RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT
* nfs: Fixing lease renewal (Benjamin Coddington)
* control hard lockup detection default
* Fix print-once on enable
* watchdog: update watchdog_thresh properly and watchdog attributes
* module: Call module notifier on failure after complete_formation()


This update also fixes the following bugs:

* Non-standard usage of the functions write_seqcount_{begin,end}() were
used in NFSv4, which caused the realtime code to try to sleep while locks
were held and produced the "scheduling while atomic" messages. The code was
modified to use the functions __write_seqcount_{begin,end}() that do not
hold any locks removing the message and allowing correct execution.

* Dracut in Red Hat Enterprise Linux 6 has a dependency on a module called
scsi_wait_scan that no longer exists on 3.x kernels. This caused the system
to display misleading messages at start-up when the obsoleted
scsi_wait_scan module was not found. To address this issue, MRG Realtime
provides a dummy scsi_wait_scan module so that the requirements for the
initramfs created by dracut are met and the boot messages are no longer
displayed. (BZ#1230403)

All kernel-rt users are advised to upgrade to these updated packages, which
correct these issues and add these enhancements. The system must be
rebooted for this update to take effect.

4. Solution:

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

5. Bugs fixed (

1203712 - CVE-2015-2922 kernel: denial of service (DoS) attack against IPv6 network stacks due to improper handling of Router Advertisements.
1208684 - CVE-2014-9715 kernel: netfilter connection tracking extensions denial of service
1218074 - CVE-2015-3636 kernel: ping sockets: use-after-free leading to local privilege escalation
1230403 - RFE: update the 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 2015 Red Hat, Inc.
Version: GnuPG v1


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