[USN-2985-2] GNU C Library regression

[Steve Beattie]

==========================================================================
Ubuntu Security Notice USN-2985-2
May 26, 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:
- glibc: GNU C Library
- eglibc: 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 versions:

Ubuntu 15.10:
  libc-bin                        2.21-0ubuntu4.3
  libc6                           2.21-0ubuntu4.3
  libc6-dev                       2.21-0ubuntu4.3

Ubuntu 14.04 LTS:
  libc-bin                        2.19-0ubuntu6.9
  libc6                           2.19-0ubuntu6.9
  libc6-dev                       2.19-0ubuntu6.9

Ubuntu 12.04 LTS:
  libc-bin                        2.15-0ubuntu10.15
  libc6                           2.15-0ubuntu10.15
  libc6-dev                       2.15-0ubuntu10.15

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

References:
  http://www.ubuntu.com/usn/usn-2985-2
  http://www.ubuntu.com/usn/usn-2985-1
  https://launchpad.net/bugs/1585614

Package Information:
  https://launchpad.net/ubuntu/+source/glibc/2.21-0ubuntu4.3
  https://launchpad.net/ubuntu/+source/eglibc/2.19-0ubuntu6.9
  https://launchpad.net/ubuntu/+source/eglibc/2.15-0ubuntu10.15

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