7.2 - RHSA-2012:1042

Problem Description:

Updated kernel packages that fix various security issues and three bugs are now available for Red Hat Enterprise Linux 6.1 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 EUS (v. 6.1) - i386, noarch, ppc64, s390x, x86_64

3. Description:

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

This update fixes the following security issues:

* A local, unprivileged user could use an integer overflow flaw in drm_mode_dirtyfb_ioctl() to cause a denial of service or escalate their privileges. (CVE-2012-0044, Important)

* It was found that the kvm_vm_ioctl_assign_device() function in the KVM (Kernel-based Virtual Machine) subsystem of a Linux kernel did not check if the user requesting device assignment was privileged or not. A local, unprivileged user on the host could assign unused PCI devices, or even devices that were in use and whose resources were not properly claimed by the respective drivers, which could result in the host crashing. (CVE-2011-4347, Moderate)

* A flaw was found in the way the Linux kernel's XFS file system implementation handled on-disk Access Control Lists (ACLs). A local, unprivileged user could use this flaw to cause a denial of service or escalate their privileges by mounting a specially-crafted disk. (CVE-2012-0038, Moderate)

* It was found that the Linux kernel's register set (regset) common infrastructure implementation did not check if the required get and set handlers were initialized. A local, unprivileged user could use this flaw to cause a denial of service by performing a register set operation with a ptrace() PTRACE_SETREGSET or PTRACE_GETREGSET request. (CVE-2012-1097, Moderate)

* A race condition was found in the Linux kernel's memory management subsystem in the way pmd_none_or_clear_bad(), when called with mmap_sem in read mode, and Transparent Huge Pages (THP) page faults interacted. A privileged user in a KVM guest with the ballooning functionality enabled could potentially use this flaw to crash the host. A local, unprivileged user could use this flaw to crash the system. (CVE-2012-1179, Moderate)

Red Hat would like to thank Chen Haogang for reporting CVE-2012-0044; Sasha Levin for reporting CVE-2011-4347; Wang Xi for reporting CVE-2012-0038; and H. Peter Anvin for reporting CVE-2012-1097.

This update also fixes the following bugs:

* When a RoCE (RDMA over Converged Ethernet) adapter with active RoCE communications was taken down suddenly (either by adapter failure or the intentional shutdown of the interface), the ongoing RoCE communications could cause the kernel to panic and render the machine unusable. A patch has been provided to protect the kernel in this situation and to pass an error up to the application still using the interface after it has been taken down instead. (BZ#799944)

* The fix for Red Hat Bugzilla bug 713494, released via RHSA-2011:0928, introduced a regression. Attempting to change the state of certain features, such as GRO (Generic Receive Offload) or TSO (TCP segment offloading), for a 10 Gigabit Ethernet card that is being used in a virtual LAN (VLAN) resulted in a kernel panic. (BZ#816974)

* If a new file was created on a Network File System version 4 (NFSv4) share, the ownership was set to nfsnobody (-2) until it was possible to upcall to the idmapper. As a consequence, subsequent file system operations could incorrectly use "-2" for the user and group IDs for the given file, causing certain operations to fail. In reported cases, this issue also caused "Viminfo file is not writable" errors for users running Vim with files on an NFSv4 share. (BZ#820960)

Users should upgrade to these updated packages, which contain backported patches to correct these issues. 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.

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 https://access.redhat.com/knowledge/articles/11258

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 (http://bugzilla.redhat.com/):

756084 - CVE-2011-4347 kernel: kvm: device assignment DoS 772894 - CVE-2012-0044 kernel: drm: integer overflow in drm_mode_dirtyfb_ioctl() 773280 - CVE-2012-0038 kernel: xfs heap overflow 799209 - CVE-2012-1097 kernel: regset: Prevent null pointer reference on readonly regsets 803793 - CVE-2012-1179 kernel: thp:__split_huge_page() mapcount != page_mapcount BUG_ON()