Bug 809687 - (CVE-2012-2100) CVE-2012-2100 kernel: ext4: fix inconsistency in ext4_fill_flex_info()
CVE-2012-2100 kernel: ext4: fix inconsistency in ext4_fill_flex_info()
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
All Linux
low Severity low
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Assigned To: Red Hat Product Security
: Security
Depends On: 809688 809689 809690 809691 809692 809693
Blocks: 809684
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Reported: 2012-04-04 00:11 EDT by Eugene Teo (Security Response)
Modified: 2015-07-31 02:49 EDT (History)
20 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2013-08-24 09:17:18 EDT
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RHEL 7.3 requirements from Atomic Host:
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Description Eugene Teo (Security Response) 2012-04-04 00:11:07 EDT
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 00:19:24 EDT
Created kernel tracking bugs for this issue

Affects: fedora-all [bug 809693]
Comment 4 Eugene Teo (Security Response) 2012-04-04 00:24:58 EDT
Upstream commit d50f2ab6 suffers from a buffer overflow issue, see
Comment 6 Vincent Danen 2012-04-12 16:25:06 EDT
This was assigned the name CVE-2012-2100:

Comment 12 Vincent Danen 2012-11-01 14:21:31 EDT

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 10:37:51 EST
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 17:34:22 EST
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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