[RHSA-2015:2401-01] Low: grub2 security, bug fix, and enhancement update

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Red Hat Security Advisory

 

Synopsis: Low: grub2 security, bug fix, and enhancement update

Advisory ID: RHSA-2015:2401-01

Product: Red Hat Enterprise Linux

Advisory URL: https://rhn.redhat.com/errata/RHSA-2015-2401.html

Issue date: 2015-11-19

CVE Names: CVE-2015-5281

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1. Summary:

 

Updated grub2 packages that fix one security issue, several bugs, and add

one enhancement are now available for Red Hat Enterprise Linux 7.

 

Red Hat Product Security has rated this update as having Low security

impact. A Common Vulnerability Scoring System (CVSS) base score, which

gives a detailed severity rating, is available from the CVE link in the

References section.

 

2. Relevant releases/architectures:

 

Red Hat Enterprise Linux Client (v. 7) - x86_64

Red Hat Enterprise Linux Client Optional (v. 7) - x86_64

Red Hat Enterprise Linux ComputeNode (v. 7) - x86_64

Red Hat Enterprise Linux ComputeNode Optional (v. 7) - x86_64

Red Hat Enterprise Linux Server (v. 7) - aarch64, ppc64, ppc64le, x86_64

Red Hat Enterprise Linux Server Optional (v. 7) - aarch64, x86_64

Red Hat Enterprise Linux Workstation (v. 7) - x86_64

Red Hat Enterprise Linux Workstation Optional (v. 7) - x86_64

 

3. Description:

 

The grub2 packages provide version 2 of the Grand Unified Bootloader

(GRUB), a highly configurable and customizable bootloader with modular

architecture. The packages support a variety of kernel formats, file

systems, computer architectures, and hardware devices.

 

It was discovered that grub2 builds for EFI systems contained modules that

were not suitable to be loaded in a Secure Boot environment. An attacker

could use this flaw to circumvent the Secure Boot mechanisms and load

non-verified code. Attacks could use the boot menu if no password was set,

or the grub2 configuration file if the attacker has root privileges on the

system. (CVE-2015-5281)

 

This update also fixes the following bugs:

 

* In one of the earlier updates, GRUB2 was modified to escape forward slash

(/) characters in several different places. In one of these places, the

escaping was unnecessary and prevented certain types of kernel command-line

arguments from being passed to the kernel correctly. With this update,

GRUB2 no longer escapes the forward slash characters in the mentioned

place, and the kernel command-line arguments work as expected. (BZ#1125404)

 

* Previously, GRUB2 relied on a timing mechanism provided by legacy

hardware, but not by the Hyper-V Gen2 hypervisor, to calibrate its timer

loop. This prevented GRUB2 from operating correctly on Hyper-V Gen2.

This update modifies GRUB2 to use a different mechanism on Hyper-V Gen2 to

calibrate the timing. As a result, Hyper-V Gen2 hypervisors now work as

expected. (BZ#1150698)

 

* Prior to this update, users who manually configured GRUB2 to use the

built-in GNU Privacy Guard (GPG) verification observed the following error

on boot:

 

alloc magic is broken at [addr]: [value] Aborted.

 

Consequently, the boot failed. The GRUB2 built-in GPG verification has been

modified to no longer free the same memory twice. As a result, the

mentioned error no longer occurs. (BZ#1167977)

 

* Previously, the system sometimes did not recover after terminating

unexpectedly and failed to reboot. To fix this problem, the GRUB2 packages

now enforce file synchronization when creating the GRUB2 configuration

file, which ensures that the required configuration files are written to

disk. As a result, the system now reboots successfully after crashing.

(BZ#1212114)

 

* Previously, if an unconfigured network driver instance was selected and

configured when the GRUB2 bootloader was loaded on a different instance,

GRUB2 did not receive notifications of the Address Resolution Protocol

(ARP) replies. Consequently, GRUB2 failed with the following error message:

 

error: timeout: could not resolve hardware address.

 

With this update, GRUB2 selects the network driver instance from which it

was loaded. As a result, ARP packets are processed correctly. (BZ#1257475)

 

In addition, this update adds the following enhancement:

 

* Sorting of GRUB2 boot menu has been improved. GRUB2 now uses the

rpmdevtools package to sort available kernels and the configuration file is

being generated correctly with the most recent kernel version listed at the

top. (BZ#1124074)

 

All grub2 users are advised to upgrade to these updated packages, which

contain backported patches to correct these issues and add this

enhancement.

 

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:

 

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

 

5. Bugs fixed (https://bugzilla.redhat.com/):

 

1001279 - grub2 can't boot new xfs CRC-capable disk format

1124074 - grub2-mkconfig wrong sorting

1125404 - [RHEL 7] grub2 improperly escapes spaces in kernel parameters

1148650 - no docs explaining what config path GRUB expects when netbooting

1177003 - yum reinstall kernel causes duplicate entry in grub menu

1211101 - grub2 fw_path variable is incorrect for x86 EFI network boot: too many path components stripped

1264103 - CVE-2015-5281 grub2: modules built in on EFI builds that allow loading arbitrary code, circumventing secure boot

 

6. Package List:

 

Red Hat Enterprise Linux Client (v. 7):

 

Source:

grub2-2.02-0.29.el7.src.rpm

 

x86_64:

grub2-2.02-0.29.el7.x86_64.rpm

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-2.02-0.29.el7.x86_64.rpm

grub2-tools-2.02-0.29.el7.x86_64.rpm

 

Red Hat Enterprise Linux Client Optional (v. 7):

 

x86_64:

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-modules-2.02-0.29.el7.x86_64.rpm

 

Red Hat Enterprise Linux ComputeNode (v. 7):

 

Source:

grub2-2.02-0.29.el7.src.rpm

 

x86_64:

grub2-2.02-0.29.el7.x86_64.rpm

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-2.02-0.29.el7.x86_64.rpm

grub2-tools-2.02-0.29.el7.x86_64.rpm

 

Red Hat Enterprise Linux ComputeNode Optional (v. 7):

 

x86_64:

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-modules-2.02-0.29.el7.x86_64.rpm

 

Red Hat Enterprise Linux Server (v. 7):

 

Source:

grub2-2.02-0.29.el7.src.rpm

 

aarch64:

grub2-debuginfo-2.02-0.29.el7.aarch64.rpm

grub2-efi-2.02-0.29.el7.aarch64.rpm

grub2-tools-2.02-0.29.el7.aarch64.rpm

 

ppc64:

grub2-2.02-0.29.el7.ppc64.rpm

grub2-debuginfo-2.02-0.29.el7.ppc64.rpm

grub2-tools-2.02-0.29.el7.ppc64.rpm

 

ppc64le:

grub2-2.02-0.29.el7.ppc64le.rpm

grub2-debuginfo-2.02-0.29.el7.ppc64le.rpm

grub2-tools-2.02-0.29.el7.ppc64le.rpm

 

x86_64:

grub2-2.02-0.29.el7.x86_64.rpm

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-2.02-0.29.el7.x86_64.rpm

grub2-tools-2.02-0.29.el7.x86_64.rpm

 

Red Hat Enterprise Linux Server Optional (v. 7):

 

aarch64:

grub2-debuginfo-2.02-0.29.el7.aarch64.rpm

grub2-efi-modules-2.02-0.29.el7.aarch64.rpm

 

x86_64:

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-modules-2.02-0.29.el7.x86_64.rpm

 

Red Hat Enterprise Linux Workstation (v. 7):

 

Source:

grub2-2.02-0.29.el7.src.rpm

 

x86_64:

grub2-2.02-0.29.el7.x86_64.rpm

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-2.02-0.29.el7.x86_64.rpm

grub2-tools-2.02-0.29.el7.x86_64.rpm

 

Red Hat Enterprise Linux Workstation Optional (v. 7):

 

x86_64:

grub2-debuginfo-2.02-0.29.el7.x86_64.rpm

grub2-efi-modules-2.02-0.29.el7.x86_64.rpm

 

These packages are GPG signed by Red Hat for security. Our key and

details on how to verify the signature are available from

https://access.redhat.com/security/team/key/

 

7. References:

 

https://access.redhat.com/security/cve/CVE-2015-5281

https://access.redhat.com/security/updates/classification/#low

 

8. Contact:

 

The Red Hat security contact is . More contact

details at https://access.redhat.com/security/team/contact/

 

Copyright 2015 Red Hat, Inc.

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