Describe CVE-2012-2100.
What is CVE-2012-2100?
The ext4_fill_flex_info function in fs/ext4/super.c in the Linux kernel before 3.2.2, on the x86 platform and unspecified other platforms, allows user-assisted remote attackers to trigger inconsistent filesystem-groups data and possibly cause a denial of service via a malformed ext4 filesystem containing a super block with a large FLEX_BG group size (aka s_log_groups_per_flex value).  NOTE: this vulnerability exists because of an incomplete fix for CVE-2009-4307..