The sisfb_ioctl function in drivers/video/sis/sis_main.c in the Linux kernel before 2.6.36-rc6 does not properly initialize a certain structure member, which allows local users to obtain potentially sensitive information from kernel stack memory via an FBIOGET_VBLANK ioctl call.
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=fd02db9de73faebc51240619c7c7f99bee9f65c7
lists.opensuse.org/opensuse-security-announce/2010-12/msg00004.html
lists.opensuse.org/opensuse-security-announce/2011-01/msg00000.html
lists.opensuse.org/opensuse-security-announce/2011-01/msg00001.html
lists.opensuse.org/opensuse-security-announce/2011-02/msg00000.html
secunia.com/advisories/42778
secunia.com/advisories/42801
www.debian.org/security/2010/dsa-2126
www.kernel.org/pub/linux/kernel/v2.6/testing/v2.6.36/ChangeLog-2.6.36-rc6
www.mandriva.com/security/advisories?name=MDVSA-2011:051
www.openwall.com/lists/oss-security/2010/09/25/2
www.openwall.com/lists/oss-security/2010/10/06/6
www.openwall.com/lists/oss-security/2010/10/07/1
www.openwall.com/lists/oss-security/2010/10/25/3
www.securityfocus.com/bid/43810
www.vupen.com/english/advisories/2011/0012
www.vupen.com/english/advisories/2011/0298
bugzilla.redhat.com/show_bug.cgi?id=648665