CVE Vulnerabilities

CVE-2011-4029

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

Published: Jul 03, 2012 | Modified: Apr 11, 2025
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
1.9 LOW
AV:L/AC:M/Au:N/C:P/I:N/A:N
RedHat/V2
4 LOW
AV:L/AC:H/Au:N/C:C/I:N/A:N
RedHat/V3
Ubuntu
HIGH

The LockServer function in os/utils.c in X.Org xserver before 1.11.2 allows local users to change the permissions of arbitrary files to 444, read those files, and possibly cause a denial of service (removed execution permission) via a symlink attack on a temporary lock file.

Weakness

The product contains a concurrent code sequence that 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 operating concurrently.

Affected Software

Name Vendor Start Version End Version
X_server X.org * 1.11.1 (including)
X_server X.org 1.11.0 (including) 1.11.0 (including)
Red Hat Enterprise Linux 6 RedHat xorg-x11-server-0:1.10.6-1.el6 *
Xorg-server Ubuntu hardy *
Xorg-server Ubuntu lucid *
Xorg-server Ubuntu maverick *
Xorg-server Ubuntu natty *
Xorg-server Ubuntu oneiric *

Extended Description

A race condition occurs within concurrent environments, and it 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. The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; 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 product.

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