The __tun_chr_ioctl function in drivers/net/tun.c in the Linux kernel before 3.6 does not initialize a certain structure, which allows local users to obtain sensitive information from kernel stack memory via a crafted application.

References

• https://nvd.nist.gov/vuln/detail/CVE-2012-6547
• torvalds/linux@a117dac
• https://www.kernel.org/pub/linux/kernel/v3.x/patch-3.6.bz2
• http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a117dacde0288f3ec60b6e5bcedae8fa37ee0dfc
• http://rhn.redhat.com/errata/RHSA-2013-0744.html
• http://www.mandriva.com/security/advisories?name=MDVSA-2013:176
• http://www.openwall.com/lists/oss-security/2013/03/05/13