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Category:   Application (Generic)  >   KVM Vendors:
(Red Hat Issues Fix) KVM Structure Initialization Error Lets Local Users Obtain Portions of Kernel Memory
SecurityTracker Alert ID:  1025691
SecurityTracker URL:
CVE Reference:   CVE-2010-3881   (Links to External Site)
Date:  Jun 22 2011
Impact:   Disclosure of system information
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   A vulnerability was reported in KVM. A local user can obtain portions of kernel memory.

Some structure padding and reserved fields in certain data structures in QEMU-KVM are not properly initialized. A privileged local host user with access to '/dev/kvm' can obtain portions of kernel stack memory.

The kvm_vcpu_events, kvm_debugregs, kvm_pit_state2, and kvm_clock_data structures are affected.

Impact:   A local privilege host user can obtain portions of kernel memory.
Solution:   Red Hat has issued a fix.

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.
Dec 20 2010 KVM Structure Initialization Error Lets Local Users Obtain Portions of Kernel Memory

 Source Message Contents

Subject:  [RHSA-2011:0883-01] Important: kernel security and bug fix update

Hash: SHA1

                   Red Hat Security Advisory

Synopsis:          Important: kernel security and bug fix update
Advisory ID:       RHSA-2011:0883-01
Product:           Red Hat Enterprise Linux
Advisory URL:
Issue date:        2011-06-21
CVE Names:         CVE-2010-3881 CVE-2010-4251 CVE-2010-4805 
                   CVE-2011-0999 CVE-2011-1010 CVE-2011-1082 
                   CVE-2011-1090 CVE-2011-1163 CVE-2011-1170 
                   CVE-2011-1171 CVE-2011-1172 CVE-2011-1182 
                   CVE-2011-1494 CVE-2011-1495 

1. Summary:

Updated kernel packages that fix several security issues and three bugs are
now available for Red Hat Enterprise Linux 6.0 Extended Update Support.

The Red Hat Security Response Team has rated this update as having
important 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:

Red Hat Enterprise Linux Server (v. 6.0.z) - i386, noarch, ppc64, s390x, x86_64

3. Description:

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

This update includes backported fixes for security issues. These issues,
except for CVE-2011-1182, only affected users of Red Hat Enterprise Linux
6.0 Extended Update Support as they have already been addressed for users
of Red Hat Enterprise Linux 6 in the 6.1 update, RHSA-2011:0542.

Security fixes:

* Buffer overflow flaws were found in the Linux kernel's Management Module
Support for Message Passing Technology (MPT) based controllers. A local,
unprivileged user could use these flaws to cause a denial of service, an
information leak, or escalate their privileges. (CVE-2011-1494,
CVE-2011-1495, Important)

* A flaw was found in the Linux kernel's networking subsystem. If the
number of packets received exceeded the receiver's buffer limit, they were
queued in a backlog, consuming memory, instead of being discarded. A remote
attacker could abuse this flaw to cause a denial of service (out-of-memory
condition). (CVE-2010-4251, CVE-2010-4805, Moderate)

* A flaw was found in the Linux kernel's Transparent Huge Pages (THP)
implementation. A local, unprivileged user could abuse this flaw to allow
the user stack (when it is using huge pages) to grow and cause a denial of
service. (CVE-2011-0999, Moderate)

* A flaw in the Linux kernel's Event Poll (epoll) implementation could
allow a local, unprivileged user to cause a denial of service.
(CVE-2011-1082, Moderate)

* An inconsistency was found in the interaction between the Linux kernel's
method for allocating NFSv4 (Network File System version 4) ACL data and
the method by which it was freed. This inconsistency led to a kernel panic
which could be triggered by a local, unprivileged user with files owned by
said user on an NFSv4 share. (CVE-2011-1090, Moderate)

* It was found that some structure padding and reserved fields in certain
data structures in KVM (Kernel-based Virtual Machine) were not initialized
properly before being copied to user-space. A privileged host user with
access to "/dev/kvm" could use this flaw to leak kernel stack memory to
user-space. (CVE-2010-3881, Low)

* A missing validation check was found in the Linux kernel's
mac_partition() implementation, used for supporting file systems created on
Mac OS operating systems. A local attacker could use this flaw to cause a
denial of service by mounting a disk that contains specially-crafted
partitions. (CVE-2011-1010, Low)

* A buffer overflow flaw in the DEC Alpha OSF partition implementation in
the Linux kernel could allow a local attacker to cause an information leak
by mounting a disk that contains specially-crafted partition tables.
(CVE-2011-1163, Low)

* Missing validations of null-terminated string data structure elements in
the do_replace(), compat_do_replace(), do_ipt_get_ctl(), do_ip6t_get_ctl(),
and do_arpt_get_ctl() functions could allow a local user who has the
CAP_NET_ADMIN capability to cause an information leak. (CVE-2011-1170,
CVE-2011-1171, CVE-2011-1172, Low)

* A missing validation check was found in the Linux kernel's signals
implementation. A local, unprivileged user could use this flaw to send
signals via the sigqueueinfo system call, with the si_code set to SI_TKILL
and with spoofed process and user IDs, to other processes. Note: This flaw
does not allow existing permission checks to be bypassed; signals can only
be sent if your privileges allow you to already do so. (CVE-2011-1182, Low)

Red Hat would like to thank Dan Rosenberg for reporting CVE-2011-1494 and
CVE-2011-1495; Nelson Elhage for reporting CVE-2011-1082; Vasiliy
Kulikov for reporting CVE-2010-3881, CVE-2011-1170, CVE-2011-1171, and
CVE-2011-1172; Timo Warns for reporting CVE-2011-1010 and CVE-2011-1163;
and Julien Tinnes of the Google Security Team for reporting CVE-2011-1182.

This update also fixes three bugs. Documentation for these changes will
be available shortly from the Technical Notes document linked to in the
References section.

4. Solution:

Users should upgrade to these updated packages, which contain
backported patches to resolve these issues, and fix the bugs noted in
the Technical Notes. The system must be rebooted for this update to
take effect.

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

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at

To install kernel packages manually, use "rpm -ivh [package]". Do not
use "rpm -Uvh" as that will remove the running kernel binaries from
your system. You may use "rpm -e" to remove old kernels after
determining that the new kernel functions properly on your system.

5. Bugs fixed (

649920 - CVE-2010-3881 kvm: arch/x86/kvm/x86.c: reading uninitialized stack memory
657303 - CVE-2010-4251 CVE-2010-4805 kernel: unlimited socket backlog DoS
678209 - CVE-2011-0999 kernel: thp: prevent hugepages during args/env copying into the user stack
679282 - CVE-2011-1010 kernel: fs/partitions: Validate map_count in Mac partition tables
681575 - CVE-2011-1082 kernel: potential kernel deadlock when creating circular epoll file structures
682641 - CVE-2011-1090 kernel: nfs4: Ensure that ACL pages sent over NFS were not allocated from the slab
688021 - CVE-2011-1163 kernel: fs/partitions: Corrupted OSF partition table infoleak
689321 - CVE-2011-1170 kernel: ipv4: netfilter: arp_tables: fix infoleak to userspace
689327 - CVE-2011-1171 kernel: ipv4: netfilter: ip_tables: fix infoleak to userspace
689345 - CVE-2011-1172 kernel: ipv6: netfilter: ip6_tables: fix infoleak to userspace
690028 - CVE-2011-1182 kernel signal spoofing issue
694021 - CVE-2011-1494 CVE-2011-1495 kernel: drivers/scsi/mpt2sas: prevent heap overflows

6. Package List:

Red Hat Enterprise Linux Server (v. 6.0.z):







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 2011 Red Hat, Inc.
Version: GnuPG v1.4.4 (GNU/Linux)


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