CVE Vulnerabilities

CVE-2016-6156

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Published: Aug 06, 2016 | Modified: Nov 28, 2016
CVSS 3.x
5.1
MEDIUM
Source:
NVD
CVSS:3.0/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.x
1.9 LOW
AV:L/AC:M/Au:N/C:N/I:N/A:P
RedHat/V2
3.3 MODERATE
AV:L/AC:M/Au:N/C:P/I:N/A:P
RedHat/V3
5.3 MODERATE
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H
Ubuntu

Race condition in the ec_device_ioctl_xcmd function in drivers/platform/chrome/cros_ec_dev.c in the Linux kernel before 4.7 allows local users to cause a denial of service (out-of-bounds array access) by changing a certain size value, aka a double fetch vulnerability.

Weakness

The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.

Affected Software

Name Vendor Start Version End Version
Linux_kernel Linux * 4.6.6
Linux Ubuntu esm-infra/xenial *
Linux Ubuntu upstream *
Linux Ubuntu wily *
Linux Ubuntu xenial *
Linux-armadaxp Ubuntu upstream *
Linux-aws Ubuntu upstream *
Linux-flo Ubuntu trusty *
Linux-flo Ubuntu upstream *
Linux-gke Ubuntu upstream *
Linux-goldfish Ubuntu trusty *
Linux-goldfish Ubuntu upstream *
Linux-grouper Ubuntu trusty *
Linux-grouper Ubuntu upstream *
Linux-hwe Ubuntu upstream *
Linux-hwe-edge Ubuntu upstream *
Linux-linaro-omap Ubuntu precise *
Linux-linaro-omap Ubuntu upstream *
Linux-linaro-shared Ubuntu precise *
Linux-linaro-shared Ubuntu upstream *
Linux-linaro-vexpress Ubuntu precise *
Linux-linaro-vexpress Ubuntu upstream *
Linux-lts-quantal Ubuntu precise *
Linux-lts-quantal Ubuntu upstream *
Linux-lts-raring Ubuntu precise *
Linux-lts-raring Ubuntu upstream *
Linux-lts-saucy Ubuntu precise *
Linux-lts-saucy Ubuntu upstream *
Linux-lts-trusty Ubuntu upstream *
Linux-lts-utopic Ubuntu upstream *
Linux-lts-vivid Ubuntu upstream *
Linux-lts-wily Ubuntu trusty *
Linux-lts-wily Ubuntu upstream *
Linux-lts-xenial Ubuntu trusty *
Linux-lts-xenial Ubuntu trusty/esm *
Linux-lts-xenial Ubuntu upstream *
Linux-maguro Ubuntu trusty *
Linux-maguro Ubuntu upstream *
Linux-mako Ubuntu trusty *
Linux-mako Ubuntu upstream *
Linux-manta Ubuntu trusty *
Linux-manta Ubuntu upstream *
Linux-qcm-msm Ubuntu precise *
Linux-qcm-msm Ubuntu upstream *
Linux-raspi2 Ubuntu upstream *
Linux-raspi2 Ubuntu vivid/ubuntu-core *
Linux-raspi2 Ubuntu wily *
Linux-raspi2 Ubuntu xenial *
Linux-snapdragon Ubuntu upstream *
Linux-snapdragon Ubuntu xenial *
Linux-ti-omap4 Ubuntu upstream *

Extended Description

This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider. A race condition occurs within concurrent environments, and is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:

A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. Programmers may assume that certain code sequences execute too quickly to be affected by an interfering code sequence; when they are not, this violates atomicity. For example, the single “x++” statement may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read (the original value of x), followed by a computation (x+1), followed by a write (save the result to x). The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the program; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable program.

Potential Mitigations

  • Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.
  • Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

References