Debian Security Advisory

DLA-609-1 linux -- LTS security update

Date Reported:
03 Sep 2016
Affected Packages:
Security database references:
In the Debian bugtracking system: Bug 827561.
In Mitre's CVE dictionary: CVE-2016-3857, CVE-2016-4470, CVE-2016-5696, CVE-2016-5829, CVE-2016-6136, CVE-2016-6480, CVE-2016-6828, CVE-2016-7118.
More information:

This update fixes the CVEs described below.

  • CVE-2016-3857

    Chiachih Wu reported two bugs in the ARM OABI compatibility layer that can be used by local users for privilege escalation. The OABI compatibility layer is enabled in all kernel flavours for armel and armhf.

  • CVE-2016-4470

    Wade Mealing of the Red Hat Product Security Team reported that in some error cases the KEYS subsystem will dereference an uninitialised pointer. A local user can use the keyctl() system call for denial of service (crash) or possibly for privilege escalation.

  • CVE-2016-5696

    Yue Cao, Zhiyun Qian, Zhongjie Wang, Tuan Dao, and Srikanth V. Krishnamurthy of the University of California, Riverside; and Lisa M. Marvel of the United States Army Research Laboratory discovered that Linux's implementation of the TCP Challenge ACK feature results in a side channel that can be used to find TCP connections between specific IP addresses, and to inject messages into those connections.

    Where a service is made available through TCP, this may allow remote attackers to impersonate another connected user to the server or to impersonate the server to another connected user. In case the service uses a protocol with message authentication (e.g. TLS or SSH), this vulnerability only allows denial of service (connection failure). An attack takes tens of seconds, so short-lived TCP connections are also unlikely to be vulnerable.

    This may be mitigated by increasing the rate limit for TCP Challenge ACKs so that it is never exceeded: sysctl net.ipv4.tcp_challenge_ack_limit=1000000000

  • CVE-2016-5829

    Several heap-based buffer overflow vulnerabilities were found in the hiddev driver, allowing a local user with access to a HID device to cause a denial of service or potentially escalate their privileges.

  • CVE-2016-6136

    Pengfei Wang discovered that the audit subsystem has a 'double-fetch' or TOCTTOU bug in its handling of special characters in the name of an executable. Where audit logging of execve() is enabled, this allows a local user to generate misleading log messages.

  • CVE-2016-6480

    Pengfei Wang discovered that the aacraid driver for Adaptec RAID controllers has a 'double-fetch' or TOCTTOU bug in its validation of FIB messages passed through the ioctl() system call. This has no practical security impact in current Debian releases.

  • CVE-2016-6828

    Marco Grassi reported a 'use-after-free' bug in the TCP implementation, which can be triggered by local users. The security impact is unclear, but might include denial of service or privilege escalation.

  • CVE-2016-7118

    Marcin Szewczyk reported that calling fcntl() on a file descriptor for a directory on an aufs filesystem would result in am oops. This allows local users to cause a denial of service. This is a Debian-specific regression introduced in version 3.2.81-1.

For Debian 7 Wheezy, these problems have been fixed in version 3.2.81-2. This version also fixes a build failure (bug #827561) for custom kernels with CONFIG_MODULES disabled, a regression in version 3.2.81-1. It also updates the PREEMPT_RT featureset to version 3.2.81-rt117.

For Debian 8 Jessie, CVE-2016-3857 has no impact; CVE-2016-4470 and CVE-2016-5829 were fixed in linux version 3.16.7-ckt25-2+deb8u3 or earlier; and the remaining issues are fixed in version 3.16.36-1+deb8u1.

We recommend that you upgrade your linux packages.

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: