Bug 809687 (CVE-2012-2100) - CVE-2012-2100 kernel: ext4: fix inconsistency in ext4_fill_flex_info()
Summary: CVE-2012-2100 kernel: ext4: fix inconsistency in ext4_fill_flex_info()
Alias: CVE-2012-2100
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 809688 809689 809690 809691 809692 809693
Blocks: 809684
TreeView+ depends on / blocked
Reported: 2012-04-04 04:11 UTC by Eugene Teo (Security Response)
Modified: 2021-02-24 12:46 UTC (History)
20 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2013-08-24 13:17:18 UTC

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2012:1445 0 normal SHIPPED_LIVE Low: kernel security and bug fix update 2012-11-13 20:37:01 UTC
Red Hat Product Errata RHSA-2012:1580 0 normal SHIPPED_LIVE Moderate: kernel security, bug fix and enhancement update 2012-12-19 03:31:48 UTC

Description Eugene Teo (Security Response) 2012-04-04 04:11:07 UTC
Commit 503358ae01b70ce6909d19dd01287093f6b6271c ("ext4: avoid divide by zero when trying to mount a corrupted file system") fixes CVE-2009-4307 by performing a sanity check on s_log_groups_per_flex, since it can be set to a bogus value by an attacker.

More info from Wang Xi:
The first commit (503358ae) fixes the division by zero.  The fix is not perfect because:
1) Theoretically, a standard-conforming C compiler could generate code that is still vulnerable to division by zero, but I was not aware of any compilers doing that.
2) Logically, we should have groups_per_flex = 2^s_log_groups_per_flex, and the fix doesn't really ensure that.  This is obviously not good, but not sure how bad the consequence would be.

Introduced by:

Upstream commit:

Comment 3 Eugene Teo (Security Response) 2012-04-04 04:19:24 UTC
Created kernel tracking bugs for this issue

Affects: fedora-all [bug 809693]

Comment 4 Eugene Teo (Security Response) 2012-04-04 04:24:58 UTC
Upstream commit d50f2ab6 suffers from a buffer overflow issue, see

Comment 6 Vincent Danen 2012-04-12 20:25:06 UTC
This was assigned the name CVE-2012-2100:


Comment 12 Vincent Danen 2012-11-01 18:21:31 UTC

This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise MRG 2.

Comment 15 errata-xmlrpc 2012-11-13 15:37:51 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5

Via RHSA-2012:1445 https://rhn.redhat.com/errata/RHSA-2012-1445.html

Comment 16 errata-xmlrpc 2012-12-18 22:34:22 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2012:1580 https://rhn.redhat.com/errata/RHSA-2012-1580.html

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