Vigil@nce: Linux kernel, NULL dereference in md
August 2009 by Vigil@nce
A local attacker can generate a NULL pointer dereference in the
suspend_lo_store()/suspend_hi_store() function of the kernel, in
order to generate a denial of service or to execute code.
Severity: 1/4
Consequences: administrator access/rights, denial of service of
computer
Provenance: user shell
Means of attack: no proof of concept, no attack
Ability of attacker: expert (4/4)
Confidence: confirmed by the editor (5/5)
Diffusion of the vulnerable configuration: low (1/3)
Creation date: 25/08/2009
IMPACTED PRODUCTS
– Debian Linux
– Linux kernel
DESCRIPTION OF THE VULNERABILITY
The md driver implements the support of disks configured as RAID.
The suspend_lo_store() and suspend_hi_store() functions of the
drivers/md/md.c file are reachable via files
/sys/block/mdX/md/suspend_lo and suspend_hi. By default, the sysfs
filesystem is mounted with mode 0644, so it is not writable by
local users. However, when the sysfs mode allows users to modify
suspend_lo and suspend_hi, they can force the md driver to
dereference a NULL pointer.
This vulnerability therefore leads to a denial of service.
A local attacker can also use this vulnerability with
VIGILANCE-VUL-8953 (https://vigilance.fr/tree/1/8953)/VIGILANCE-VUL-8861
(https://vigilance.fr/tree/1/8861) in order to elevate his
privileges.
CHARACTERISTICS
Identifiers: CVE-2009-2849, DSA 1872-1, VIGILANCE-VUL-8973
http://vigilance.fr/vulnerability/Linux-kernel-NULL-dereference-in-md-8973