Topic

Updated glibc packages that fix two security issues and two bugs are now
available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Critical 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.

Description

The glibc packages provide the standard C libraries (libc), POSIX
thread libraries (libpthread), standard math libraries (libm), and the
name service cache daemon (nscd) used by multiple programs on the
system. Without these libraries, the Linux system cannot function
correctly.

A stack-based buffer overflow was found in the way the libresolv library
performed dual A/AAAA DNS queries. A remote attacker could create a
specially crafted DNS response which could cause libresolv to crash or,
potentially, execute code with the permissions of the user running the
library. Note: this issue is only exposed when libresolv is called from the
nss_dns NSS service module. (CVE-2015-7547)

It was discovered that the calloc implementation in glibc could return
memory areas which contain non-zero bytes. This could result in unexpected
application behavior such as hangs or crashes. (CVE-2015-5229)

The CVE-2015-7547 issue was discovered by the Google Security Team and Red
Hat. Red Hat would like to thank Jeff Layton for reporting the
CVE-2015-5229 issue.

This update also fixes the following bugs:

• The existing implementation of the "free" function causes all memory

pools beyond the first to return freed memory directly to the operating
system as quickly as possible. This can result in performance degradation
when the rate of free calls is very high. The first memory pool (the main
pool) does provide a method to rate limit the returns via M_TRIM_THRESHOLD,
but this method is not available to subsequent memory pools.

With this update, the M_TRIM_THRESHOLD method is extended to apply to all
memory pools, which improves performance for threads with very high amounts
of free calls and limits the number of "madvise" system calls. The change
also increases the total transient memory usage by processes because the
trim threshold must be reached before memory can be freed.

To return to the previous behavior, you can either set M_TRIM_THRESHOLD
using the "mallopt" function, or set the MALLOC_TRIM_THRESHOLD environment
variable to 0. (BZ#1298930)

• On the little-endian variant of 64-bit IBM Power Systems (ppc64le), a bug

in the dynamic loader could cause applications compiled with profiling
enabled to fail to start with the error "monstartup: out of memory".
The bug has been corrected and applications compiled for profiling now
start correctly. (BZ#1298956)

All glibc users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues.

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

Affected Products

• Red Hat Enterprise Linux Server 7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.2 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 x86_64
• Red Hat Enterprise Linux Server - AUS 7.4 x86_64
• Red Hat Enterprise Linux Server - AUS 7.3 x86_64
• Red Hat Enterprise Linux Server - AUS 7.2 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.4 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.3 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.2 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.4 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.3 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.2 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux Server from RHUI 7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.4 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.3 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.2 x86_64
• Red Hat Enterprise Linux for Power, little endian 7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.6 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.5 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.4 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.3 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.2 ppc64le
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux Server - TUS 7.3 x86_64
• Red Hat Enterprise Linux Server - TUS 7.2 x86_64
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.7 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.6 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.4 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.3 ppc64le
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.4 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.3 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.2 x86_64

Fixes

• BZ - 1256285 - CVE-2015-5229 glibc: calloc may return non-zero memory
• BZ - 1293532 - CVE-2015-7547 glibc: getaddrinfo stack-based buffer overflow
• BZ - 1298956 - "monstartup: out of memory" on PPC64LE [rhel-7.2.z]

CVEs

• CVE-2015-5229
• CVE-2015-7547

References