Ubuntu Security Notice USN-2985-2

26th May, 2016

eglibc, glibc regression

A security issue affects these releases of Ubuntu and its
derivatives:

• Ubuntu 15.10
• Ubuntu 14.04 LTS
• Ubuntu 12.04 LTS

Summary

USN-2985-1 introduced a regression in the GNU C Library.

Software description

• eglibc
  – GNU C Library

• glibc
  – GNU C Library

Details

USN-2985-1 fixed vulnerabilities in the GNU C Library. The fix for
CVE-2014-9761 introduced a regression which affected applications that
use the libm library but were not fully restarted after the upgrade.
This update removes the fix for CVE-2014-9761 and a future update
will be provided to address this issue.

We apologize for the inconvenience.

Original advisory details:

Martin Carpenter discovered that pt_chown in the GNU C Library did not
properly check permissions for tty files. A local attacker could use this
to gain administrative privileges or expose sensitive information.
(CVE-2013-2207, CVE-2016-2856)

Robin Hack discovered that the Name Service Switch (NSS) implementation in
the GNU C Library did not properly manage its file descriptors. An attacker
could use this to cause a denial of service (infinite loop).
(CVE-2014-8121)

Joseph Myers discovered that the GNU C Library did not properly handle long
arguments to functions returning a representation of Not a Number (NaN). An
attacker could use this to cause a denial of service (stack exhaustion
leading to an application crash) or possibly execute arbitrary code.
(CVE-2014-9761)

Arjun Shankar discovered that in certain situations the nss_dns code in the
GNU C Library did not properly account buffer sizes when passed an
unaligned buffer. An attacker could use this to cause a denial of service
or possibly execute arbitrary code. (CVE-2015-1781)

Sumit Bose and Lukas Slebodnik discovered that the Name Service
Switch (NSS) implementation in the GNU C Library did not handle long
lines in the files databases correctly. A local attacker could use
this to cause a denial of service (application crash) or possibly
execute arbitrary code. (CVE-2015-5277)

Adam Nielsen discovered that the strftime function in the GNU C Library did
not properly handle out-of-range argument data. An attacker could use this
to cause a denial of service (application crash) or possibly expose
sensitive information. (CVE-2015-8776)

Hector Marco and Ismael Ripoll discovered that the GNU C Library allowed
the pointer-guarding protection mechanism to be disabled by honoring the
LD_POINTER_GUARD environment variable across privilege boundaries. A local
attacker could use this to exploit an existing vulnerability more easily.
(CVE-2015-8777)

Szabolcs Nagy discovered that the hcreate functions in the GNU C Library
did not properly check its size argument, leading to an integer overflow.
An attacker could use to cause a denial of service (application crash) or
possibly execute arbitrary code. (CVE-2015-8778)

Maksymilian Arciemowicz discovered a stack-based buffer overflow in the
catopen function in the GNU C Library when handling long catalog names. An
attacker could use this to cause a denial of service (application crash) or
possibly execute arbitrary code. (CVE-2015-8779)

Florian Weimer discovered that the getnetbyname implementation in the GNU C
Library did not properly handle long names passed as arguments. An attacker
could use to cause a denial of service (stack exhaustion leading to an
application crash). (CVE-2016-3075)

Update instructions

The problem can be corrected by updating your system to the following
package version:

Ubuntu 15.10:

libc-bin

2.21-0ubuntu4.3

libc6-dev

2.21-0ubuntu4.3

libc6

2.21-0ubuntu4.3

Ubuntu 14.04 LTS:

libc-bin

2.19-0ubuntu6.9

libc6-dev

2.19-0ubuntu6.9

libc6

2.19-0ubuntu6.9

Ubuntu 12.04 LTS:

libc-bin

2.15-0ubuntu10.15

libc6-dev

2.15-0ubuntu10.15

libc6

2.15-0ubuntu10.15

To update your system, please follow these instructions:
https://wiki.ubuntu.com/Security/Upgrades.

After a standard system update you need to reboot your computer to
make all the necessary changes.

References

LP: 1585614