Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 6 | perf +15 | 2.6.32-279.19.1.el6 | RHSA-2012:1580 |
| RHEL 5 | kernel +12 | 2.6.18-308.20.1.el5 | RHSA-2012:1445 |
Advisories 2
- RHSA-2012:1580 Red Hat Security Advisory: kernel security, bug fix and enhancement update Red Hat Security Advisories (RHSA) · Jun 28, 2026
- RHSA-2012:1445 Red Hat Security Advisory: kernel security and bug fix update Red Hat Security Advisories (RHSA) · Jun 26, 2026
References
- RHSA-2012:1580 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=809687
- RHSA-2012:1445 vendor-advisory
- 53414 vdb-entry
- [oss-security] 20120412 Re: fix to CVE-2009-4307 mailing-list
- http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=d50f2ab6f050311dbf7b8f5501b25f0bf64a439b
- https://github.com/torvalds/linux/commit/d50f2ab6f050311dbf7b8f5501b25f0bf64a439b
- http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.2.2