The Vigil@nce team watches public vulnerabilities impacting your computers, and then offers security solutions, a vigilance database and tools to fix them.

Vulnerability of Linux kernel: denial of service via current_clocksource

Synthesis of the vulnerability 

When the kernel is compiled without GENERIC_TIME, a local attacker can access to current_clocksource, in order to stop the kernel.
Impacted systems: Linux.
Severity of this alert: 1/4.
Creation date: 23/06/2010.
Références of this alert: BID-41079, CVE-2010-2243, VIGILANCE-VUL-9725.

Description of the vulnerability 

The GENERIC_TIME compilation option enables the synchronization of time using available counters. This option is enabled by default on recent kernels.

When GENERIC_TIME is disabled, the clocksource_done_booting() function of the kernel/time/clocksource.c file does not initialize the curr_clocksource variable. A local attacker can therefore read /sys/devices/system/clocksource/clocksource0/current_clocksource, in order to force the kernel to use an invalid value, which stops it.

When the kernel is compiled without GENERIC_TIME, a local attacker can therefore access to current_clocksource, in order to stop the kernel.
Full bulletin, software filtering, emails, fixes, ... (Request your free trial)

This computer vulnerability bulletin impacts software or systems such as Linux.

Our Vigil@nce team determined that the severity of this vulnerability bulletin is low.

The trust level is of type confirmed by the editor, with an origin of user shell.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a technician ability can exploit this threat note.

Solutions for this threat 

Linux kernel: patch for current_clocksource.
A patch is available in information sources.
Full bulletin, software filtering, emails, fixes, ... (Request your free trial)

Computer vulnerabilities tracking service 

Vigil@nce provides a networks vulnerabilities alert. The Vigil@nce computer vulnerability tracking service alerts your teams of vulnerabilities or threats impacting your information system.