The do_insn_fetch function in arch/x86/kvm/emulate.c in the x86 emulator in the KVM subsystem in the Linux kernel before 2.6.32-rc8-next-20091125 tries to interpret instructions that contain too many bytes to be valid, which allows guest OS users to cause a denial of service (increased scheduling latency) on the host OS via unspecified manipulations related to SMP support.

From Red Hat Security Advisory 2009:1659 :

Updated kvm packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 5.

This update has been rated as having moderate security impact by the Red Hat Security Response Team.

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for the standard Red Hat Enterprise Linux kernel.

On x86 platforms, the do_insn_fetch() function did not limit the amount of instruction bytes fetched per instruction. Users in guest operating systems could leverage this flaw to cause large latencies on SMP hosts that could lead to a local denial of service on the host operating system. This update fixes this issue by imposing the architecturally-defined 15 byte length limit for instructions.
(CVE-2009-4031)

This update also fixes the following bugs :

* performance problems occurred when using the qcow2 image format with the qemu-kvm -drive 'cache=none' option (the default setting when not specified otherwise). This could cause guest operating system installations to take hours. With this update, performance patches have been backported so that using the qcow2 image format with the 'cache=none' option no longer causes performance issues. (BZ#520693)

* when using the virtual vm8086 mode, bugs in the emulated hardware task switching implementation may have, in some situations, caused older guest operating systems to malfunction. (BZ#532031)

* Windows Server 2003 guests (32-bit) with more than 4GB of memory may have crashed during reboot when using the default qemu-kvm CPU settings. (BZ#532043)

* with Red Hat Enterprise Virtualization, guests continued to run after encountering disk read errors. This could have led to their file systems becoming corrupted (but not the host's), notably in environments that use networked storage. With this update, the qemu-kvm -drive 'werror=stop' option now applies not only to write errors but also to read errors: When using this option, guests will pause on disk read and write errors.

By default, guests managed by Red Hat Enterprise Virtualization use the 'werror=stop' option. This option is not used by default for guests managed by libvirt. (BZ#537334, BZ#540406)

* the para-virtualized block driver (virtio-blk) silently ignored read errors when accessing disk images. With this update, the driver correctly signals the read error to the guest. (BZ#537334)

All KVM users should upgrade to these updated packages, which contain backported patches to resolve these issues. Note: The procedure in the Solution section must be performed before this update will take effect.

The remote Redhat Enterprise Linux 5 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2009:1659 advisory.

  - kernel: KVM: x86 emulator: limit instructions to 15 bytes (CVE-2009-4031)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

CVE-2009-4031 kernel: KVM: x86 emulator: limit instructions to 15 bytes

On x86 platforms, the do_insn_fetch() function did not limit the amount of instruction bytes fetched per instruction. Users in guest operating systems could leverage this flaw to cause large latencies on SMP hosts that could lead to a local denial of service on the host operating system. This update fixes this issue by imposing the architecturally-defined 15 byte length limit for instructions.
(CVE-2009-4031)

This update also fixes the following bugs :

  - performance problems occurred when using the qcow2 image     format with the qemu-kvm -drive 'cache=none' option (the     default setting when not specified otherwise). This     could cause guest operating system installations to take     hours. With this update, performance patches have been     backported so that using the qcow2 image format with the     'cache=none' option no longer causes performance issues.
    (BZ#520693)

  - when using the virtual vm8086 mode, bugs in the emulated     hardware task switching implementation may have, in some     situations, caused older guest operating systems to     malfunction. (BZ#532031)

  - Windows Server 2003 guests (32-bit) with more than 4GB     of memory may have crashed during reboot when using the     default qemu-kvm CPU settings. (BZ#532043)

  - with Scientific Linux Virtualization, guests continued     to run after encountering disk read errors. This could     have led to their file systems becoming corrupted (but     not the host's), notably in environments that use     networked storage. With this update, the qemu-kvm -drive     'werror=stop' option now applies not only to write     errors but also to read errors: When using this option,     guests will pause on disk read and write errors.

By default, guests managed by Scientific Linux Virtualization use the 'werror=stop' option. This option is not used by default for guests managed by libvirt. (BZ#537334, BZ#540406)

  - the para-virtualized block driver (virtio-blk) silently     ignored read errors when accessing disk images. With     this update, the driver correctly signals the read error     to the guest. (BZ#537334)

This update of the openSUSE 11.2 kernel contains a lot of bug and security fixes.

Following security issues were fixed: CVE-2010-0622: The wake_futex_pi function in kernel/futex.c in the Linux kernel does not properly handle certain unlock operations for a Priority Inheritance (PI) futex, which allows local users to cause a denial of service (OOPS) and possibly have unspecified other impact via vectors involving modification of the futex value from user space.

CVE-2010-0623: The futex_lock_pi function in kernel/futex.c in the Linux kernel does not properly manage a certain reference count, which allows local users to cause a denial of service (OOPS) via vectors involving an unmount of an ext3 filesystem.

CVE-2010-0415: The do_pages_move function in mm/migrate.c in the Linux kernel does not validate node values, which allows local users to read arbitrary kernel memory locations, cause a denial of service (OOPS), and possibly have unspecified other impact by specifying a node that is not part of the kernel's node set.

CVE-2010-0410: drivers/connector/connector.c in the Linux kernel allows local users to cause a denial of service (memory consumption and system crash) by sending the kernel many NETLINK_CONNECTOR messages.

CVE-2009-4031: The do_insn_fetch function in arch/x86/kvm/emulate.c in the x86 emulator in the KVM subsystem in the Linux kernel tries to interpret instructions that contain too many bytes to be valid, which allows guest OS users to cause a denial of service (increased scheduling latency) on the host OS via unspecified manipulations related to SMP support.

This update also contains a large rollup of fixes for the rt2860 and rt3090 wireless drivers from the mainline kernel.

Several vulnerabilities have been discovered in kvm, a full virtualization system. The Common Vulnerabilities and Exposures project identifies the following problems :

  - CVE-2009-3638     It was discovered an Integer overflow in the     kvm_dev_ioctl_get_supported_cpuid function. This allows     local users to have an unspecified impact via a     KVM_GET_SUPPORTED_CPUID request to the     kvm_arch_dev_ioctl function.

  - CVE-2009-3722     It was discovered that the handle_dr function in the KVM     subsystem does not properly verify the Current Privilege     Level (CPL) before accessing a debug register, which     allows guest OS users to cause a denial of service     (trap) on the host OS via a crafted application.

  - CVE-2009-4031     It was discovered that the do_insn_fetch function in the     x86 emulator in the KVM subsystem tries to interpret     instructions that contain too many bytes to be valid,     which allows guest OS users to cause a denial of service     (increased scheduling latency) on the host OS via     unspecified manipulations related to SMP support.

Amerigo Wang and Eric Sesterhenn discovered that the HFS and ext4 filesystems did not correctly check certain disk structures. If a user were tricked into mounting a specially crafted filesystem, a remote attacker could crash the system or gain root privileges.
(CVE-2009-4020, CVE-2009-4308)

It was discovered that FUSE did not correctly check certain requests.
A local attacker with access to FUSE mounts could exploit this to crash the system or possibly gain root privileges. Ubuntu 9.10 was not affected. (CVE-2009-4021)

It was discovered that KVM did not correctly decode certain guest instructions. A local attacker in a guest could exploit this to trigger high scheduling latency in the host, leading to a denial of service. Ubuntu 6.06 was not affected. (CVE-2009-4031)

It was discovered that the OHCI fireware driver did not correctly handle certain ioctls. A local attacker could exploit this to crash the system, or possibly gain root privileges. Ubuntu 6.06 was not affected. (CVE-2009-4138)

Tavis Ormandy discovered that the kernel did not correctly handle O_ASYNC on locked files. A local attacker could exploit this to gain root privileges. Only Ubuntu 9.04 and 9.10 were affected.
(CVE-2009-4141)

Neil Horman and Eugene Teo discovered that the e1000 and e1000e network drivers did not correctly check the size of Ethernet frames.
An attacker on the local network could send specially crafted traffic to bypass packet filters, crash the system, or possibly gain root privileges. (CVE-2009-4536, CVE-2009-4538)

It was discovered that 'print-fatal-signals' reporting could show arbitrary kernel memory contents. A local attacker could exploit this, leading to a loss of privacy. By default this is disabled in Ubuntu and did not affect Ubuntu 6.06. (CVE-2010-0003)

Olli Jarva and Tuomo Untinen discovered that IPv6 did not correctly handle jumbo frames. A remote attacker could exploit this to crash the system, leading to a denial of service. Only Ubuntu 9.04 and 9.10 were affected. (CVE-2010-0006)

Florian Westphal discovered that bridging netfilter rules could be modified by unprivileged users. A local attacker could disrupt network traffic, leading to a denial of service. (CVE-2010-0007)

Al Viro discovered that certain mremap operations could leak kernel memory. A local attacker could exploit this to consume all available memory, leading to a denial of service. (CVE-2010-0291).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Updated kvm packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 5.

This update has been rated as having moderate security impact by the Red Hat Security Response Team.

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. KVM is a Linux kernel module built for the standard Red Hat Enterprise Linux kernel.

On x86 platforms, the do_insn_fetch() function did not limit the amount of instruction bytes fetched per instruction. Users in guest operating systems could leverage this flaw to cause large latencies on SMP hosts that could lead to a local denial of service on the host operating system. This update fixes this issue by imposing the architecturally-defined 15 byte length limit for instructions.
(CVE-2009-4031)

This update also fixes the following bugs :

* performance problems occurred when using the qcow2 image format with the qemu-kvm -drive 'cache=none' option (the default setting when not specified otherwise). This could cause guest operating system installations to take hours. With this update, performance patches have been backported so that using the qcow2 image format with the 'cache=none' option no longer causes performance issues. (BZ#520693)

* when using the virtual vm8086 mode, bugs in the emulated hardware task switching implementation may have, in some situations, caused older guest operating systems to malfunction. (BZ#532031)

* Windows Server 2003 guests (32-bit) with more than 4GB of memory may have crashed during reboot when using the default qemu-kvm CPU settings. (BZ#532043)

* with Red Hat Enterprise Virtualization, guests continued to run after encountering disk read errors. This could have led to their file systems becoming corrupted (but not the host's), notably in environments that use networked storage. With this update, the qemu-kvm -drive 'werror=stop' option now applies not only to write errors but also to read errors: When using this option, guests will pause on disk read and write errors.

By default, guests managed by Red Hat Enterprise Virtualization use the 'werror=stop' option. This option is not used by default for guests managed by libvirt. (BZ#537334, BZ#540406)

* the para-virtualized block driver (virtio-blk) silently ignored read errors when accessing disk images. With this update, the driver correctly signals the read error to the guest. (BZ#537334)

All KVM users should upgrade to these updated packages, which contain backported patches to resolve these issues. Note: The procedure in the Solution section must be performed before this update will take effect.

Update to kernel 2.6.27.41:
http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.27.39 http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.27.40 http://www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.27.41

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
67971	Oracle Linux 5 : kvm (ELSA-2009-1659)	Nessus	Oracle Linux Local Security Checks	high
63909	RHEL 5 : kvm (RHSA-2009:1659)	Nessus	Red Hat Local Security Checks	high
60704	Scientific Linux Security Update : kvm on SL5.4 x86_64	Nessus	Scientific Linux Local Security Checks	high
45128	openSUSE Security Update : kernel (kernel-2146)	Nessus	SuSE Local Security Checks	high
44827	Debian DSA-1962-1 : kvm - several vulnerabilities	Nessus	Debian Local Security Checks	high
44399	Ubuntu 6.06 LTS / 8.04 LTS / 8.10 / 9.04 / 9.10 : linux, linux-source-2.6.15 vulnerabilities (USN-894-1)	Nessus	Ubuntu Local Security Checks	critical
43811	CentOS 5 : kvm (CESA-2009:1659)	Nessus	CentOS Local Security Checks	high
43125	Fedora 10 : kernel-2.6.27.41-170.2.117.fc10 (2009-13098)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2009-4031

high

Tenable Plugins

high

high

high

high

high

critical

high

high