The EXT4_IOC_MOVE_EXT (aka move extents) ioctl implementation in the ext4 filesystem in the Linux kernel before 2.6.32-git6 allows local users to overwrite arbitrary files via a crafted request, related to insufficient checks for file permissions.
https://www.redhat.com/archives/fedora-package-announce/2009-December/msg00702.html
https://bugzilla.redhat.com/show_bug.cgi?id=544471
http://www.vupen.com/english/advisories/2009/3468
http://www.ubuntu.com/usn/USN-869-1
http://www.theregister.co.uk/2009/12/11/linux_kernel_bugs_patched/
http://www.securityfocus.com/bid/37277
http://www.mandriva.com/security/advisories?name=MDVSA-2009:329
http://www.kernel.org/pub/linux/kernel/v2.6/snapshots/patch-2.6.32-git6.log
http://secunia.com/advisories/38017
http://secunia.com/advisories/37686
http://secunia.com/advisories/37658
http://lkml.org/lkml/2009/12/9/255
http://lists.opensuse.org/opensuse-security-announce/2010-01/msg00000.html