The tty_open function in drivers/tty/tty_io.c in the Linux kernel before 3.1.1 mishandles a driver-lookup failure, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via crafted access to a device file under the /dev/pts directory. (CVE-2011-5321)

Impact

A local, unprivileged user may exploit this vulnerability and create a situation where the system stops responding.

In the default configuration, only an administrator user has advanced shell access. If a non-administrator user is given advanced shell access in a non-default configuration, then the possibility of privilege escalation increases the exposure of this vulnerability.

Updated kernel packages that fix multiple security issues, several bugs, and add one enhancement are now available for Red Hat Enterprise Linux 6.

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

The kernel packages contain the Linux kernel, the core of any Linux operating system.

* A NULL pointer dereference flaw was found in the way the Linux kernel's virtual console implementation handled reference counting when accessing pseudo-terminal device files (/dev/pts/*). A local, unprivileged attacker could use this flaw to crash the system.
(CVE-2011-5321, Moderate)

* It was found that the Linux kernel's ping socket implementation did not properly handle socket unhashing during spurious disconnects, which could lead to a use-after-free flaw. On x86-64 architecture systems, a local user able to create ping sockets could use this flaw to crash the system. On non-x86-64 architecture systems, a local user able to create ping sockets could use this flaw to escalate their privileges on the system. (CVE-2015-3636, Moderate)

* An integer overflow flaw was found in the way the Linux kernel randomized the stack for processes on certain 64-bit architecture systems, such as x86-64, causing the stack entropy to be reduced by four. (CVE-2015-1593, Low)

* A flaw was found in the way the Linux kernel's 32-bit emulation implementation handled forking or closing of a task with an 'int80' entry. A local user could potentially use this flaw to escalate their privileges on the system. (CVE-2015-2830, Low)

* It was found that the Linux kernel's TCP/IP protocol suite implementation for IPv6 allowed the Hop Limit value to be set to a smaller value than the default one. An attacker on a local network could use this flaw to prevent systems on that network from sending or receiving network packets. (CVE-2015-2922, Low)

These updated kernel packages also include numerous bug fixes and one enhancement. Space precludes documenting all of these changes in this advisory. For information on the most significant of these changes, users are directed to the following article on the Red Hat Customer Portal :

https://access.redhat.com/articles/1506133

All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add this enhancement. The system must be rebooted for this update to take effect.

* A NULL pointer dereference flaw was found in the way the Linux kernel's virtual console implementation handled reference counting when accessing pseudo-terminal device files (/dev/pts/*). A local, unprivileged attacker could use this flaw to crash the system.
(CVE-2011-5321, Moderate)

* It was found that the Linux kernel's ping socket implementation did not properly handle socket unhashing during spurious disconnects, which could lead to a use-after-free flaw. On x86-64 architecture systems, a local user able to create ping sockets could use this flaw to crash the system. On non-x86-64 architecture systems, a local user able to create ping sockets could use this flaw to escalate their privileges on the system. (CVE-2015-3636, Moderate)

* An integer overflow flaw was found in the way the Linux kernel randomized the stack for processes on certain 64-bit architecture systems, such as x86-64, causing the stack entropy to be reduced by four. (CVE-2015-1593, Low)

* A flaw was found in the way the Linux kernel's 32-bit emulation implementation handled forking or closing of a task with an 'int80' entry. A local user could potentially use this flaw to escalate their privileges on the system. (CVE-2015-2830, Low)

* It was found that the Linux kernel's TCP/IP protocol suite implementation for IPv6 allowed the Hop Limit value to be set to a smaller value than the default one. An attacker on a local network could use this flaw to prevent systems on that network from sending or receiving network packets. (CVE-2015-2922, Low)

For information on the most significant of these changes, users are directed to the following article on the Red Hat Customer Portal :

The system must be rebooted for this update to take effect.

The linux-2.6 update issued as DLA-246-1 caused regressions. This update corrects the defective patches applied in that update causing these problems. For reference the original advisory text follows.

This update fixes the CVEs described below.

CVE-2011-5321

Jiri Slaby discovered that tty_driver_lookup_tty() may leak a reference to the tty driver. A local user could use this flaw to crash the system.

CVE-2012-6689

Pablo Neira Ayuso discovered that non-root user-space processes can send forged Netlink notifications to other processes. A local user could use this flaw for denial of service or privilege escalation.

CVE-2014-3184

Ben Hawkes discovered that various HID drivers may over-read the report descriptor buffer, possibly resulting in a crash if a HID with a crafted descriptor is plugged in.

CVE-2014-8159

It was found that the Linux kernel's InfiniBand/RDMA subsystem did not properly sanitize input parameters while registering memory regions from user space via the (u)verbs API. A local user with access to a /dev/infiniband/uverbsX device could use this flaw to crash the system or, potentially, escalate their privileges on the system.

CVE-2014-9683

Dmitry Chernenkov discovered that eCryptfs writes past the end of the allocated buffer during encrypted filename decoding, resulting in local denial of service.

CVE-2014-9728 / CVE-2014-9729 / CVE-2014-9730 / CVE-2014-9731 / CVE-2015-4167

Carl Henrik Lunde discovered that the UDF implementation is missing several necessary length checks. A local user that can mount devices could use these various flaws to crash the system, to leak information from the kernel, or possibly for privilege escalation.

CVE-2015-1805

Red Hat discovered that the pipe iovec read and write implementations may iterate over the iovec twice but will modify the iovec such that the second iteration accesses the wrong memory. A local user could use this flaw to crash the system or possibly for privilege escalation.
This may also result in data corruption and information leaks in pipes between non-malicious processes.

CVE-2015-2041

Sasha Levin discovered that the LLC subsystem exposed some variables as sysctls with the wrong type. On a 64-bit kernel, this possibly allows privilege escalation from a process with CAP_NET_ADMIN capability; it also results in a trivial information leak.

CVE-2015-2042

Sasha Levin discovered that the RDS subsystem exposed some variables as sysctls with the wrong type. On a 64-bit kernel, this results in a trivial information leak.

CVE-2015-2830

Andrew Lutomirski discovered that when a 64-bit task on an amd64 kernel makes a fork(2) or clone(2) system call using int $0x80, the 32-bit compatibility flag is set (correctly) but is not cleared on return. As a result, both seccomp and audit will misinterpret the following system call by the task(s), possibly leading to a violation of security policy.

CVE-2015-2922

Modio AB discovered that the IPv6 subsystem would process a router advertisement that specifies no route but only a hop limit, which would then be applied to the interface that received it. This can result in loss of IPv6 connectivity beyond the local network.

This may be mitigated by disabling processing of IPv6 router advertisements if they are not needed: sysctl net.ipv6.conf.default.accept_ra=0 sysctl net.ipv6.conf.<interface>.accept_ra=0

CVE-2015-3339

It was found that the execve(2) system call can race with inode attribute changes made by chown(2). Although chown(2) clears the setuid/setgid bits of a file if it changes the respective owner ID, this race condition could result in execve(2) setting effective uid/gid to the new owner ID, a privilege escalation.

For the oldoldstable distribution (squeeze), these problems have been fixed in version 2.6.32-48squeeze12.

For the oldstable distribution (wheezy), these problems were fixed in linux version 3.2.68-1+deb7u1 or earlier, except for CVE-2015-1805 and CVE-2015-4167 which will be fixed soon.

For the stable distribution (jessie), these problems were fixed in linux version 3.16.7-ckt11-1 or earlier, except for CVE-2015-4167 which will be fixed later.

We recommend that you upgrade your linux-2.6 packages.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Oracle Linux 6 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2015-1221 advisory.

    - [fs] pipe: fix pipe corruption and iovec overrun on partial copy (Seth Jennings) [1202860 1185166]     {CVE-2015-1805}
    - [net] ipv4: Missing sk_nulls_node_init in ping_unhash (Denys Vlasenko) [1218102 1218103] {CVE-2015-3636}
    - [x86] asm/entry/64: Remove a bogus 'ret_from_fork' optimization (Mateusz Guzik) [1209232 1209233]     {CVE-2015-2830}
    - [x86] mm: Linux stack ASLR implementation (Jacob Tanenbaum) [1195682 1195683] {CVE-2015-1593}

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Published	Updated	Severity
90455	F5 Networks BIG-IP : Linux kernel vulnerability (K21632201)	Nessus	F5 Networks Local Security Checks	4/13/2016	3/10/2021	medium
84758	RHEL 6 : kernel (RHSA-2015:1221)	Nessus	Red Hat Local Security Checks	7/15/2015	10/24/2019	medium
84790	Scientific Linux Security Update : kernel on SL6.x i386/x86_64 (20150714)	Nessus	Scientific Linux Local Security Checks	7/16/2015	1/14/2021	medium
84769	CentOS 6 : kernel (CESA-2015:1221)	Nessus	CentOS Local Security Checks	7/16/2015	1/4/2021	medium
84252	Debian DLA-246-2 : linux-2.6 regression update	Nessus	Debian Local Security Checks	6/18/2015	1/11/2021	high
84757	Oracle Linux 6 : kernel (ELSA-2015-1221)	Nessus	Oracle Linux Local Security Checks	7/15/2015	10/22/2024	medium

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