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SYNTHESIS OF THE VULNERABILITY

A local attacker can force a call to request_module(), to disable
the Out-Of-Memory-Killer, in order to overload the memory.

Impacted products: Linux

Severity: 1/4

Creation date: 03/09/2012

DESCRIPTION OF THE VULNERABILITY

The request_module() function is used by the kernel to load a
module. It is for example called during the creation of a socket
using a module.

The Out-Of-Memory-Killer monitors processes consuming memory, and
decides to kill them, in order to free memory for other processes.
So, a malicious application cannot block the system.

However, if a loaded process forces a call to request_module(),
the Out-Of-Memory-Killer cannot kill the process which uses a
state TASK_UNINTERRUPTIBLE. The Out-Of-Memory-Killer is then
disabled.

A local attacker can therefore force a call to request_module(),
to disable the Out-Of-Memory-Killer, in order to overload the
memory.

ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN

http://vigilance.fr/vulnerability/Linux-kernel-denial-of-service-via-request-module-11915