Original URL: http://www.theregister.co.uk/2009/12/03/linux_kernel_bug_patched/

Linux kernel cured of remote panic-attack bug

Get your BUG_ON

By Dan Goodin

Posted in Security, 3rd December 2009 20:04 GMT

Developers of the Linux kernel have patched a bug that allowed attackers to remotely crash a machine by sending it malicious Wi-Fi signals.

The flaw in the delBA handling of mac80211 has been fixed in version 2.6.32, the latest stable release of the Linux kernel. Various distributions of the open-source operating system have already acknowledged the issue and are expected to push out updates soon. Based on developer notes on the official Linux website, the vulnerability appears to have been introduced in February.

The flaw stemmed from faulty code that called the BUG_ON macro before various checks were performed. That raised the possibility of NULL being passed to TX/RX_STOP parameter, which in turn caused a kernel panic. The end result: an attacker within Wi-Fi range of a vulnerable machine might be able to effectively shut it down.

The bug was discovered by Johannes Berg, who found a separate flaw related to mac80211 that was fixed in the latest release. Details about both flaw are here and here. ®