Bug 817430 - (CVE-2012-2133) CVE-2012-2133 kernel: use after free bug in "quota" handling
CVE-2012-2133 kernel: use after free bug in "quota" handling
Status: CLOSED ERRATA
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
medium Severity medium
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Assigned To: Red Hat Product Security
impact=moderate,public=20120322,repor...
: Security
: 815065 (view as bug list)
Depends On: 843034 843035 843036 843037 843038 927272
Blocks: 815174
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Reported: 2012-04-29 21:05 EDT by Eugene Teo (Security Response)
Modified: 2015-07-31 11:30 EDT (History)
20 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Last Closed: 2013-04-16 15:19:16 EDT
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RHEL 7.3 requirements from Atomic Host:
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Description Eugene Teo (Security Response) 2012-04-29 21:05:57 EDT
There is a use after free bug in the kernel hugetlb code. The bug can allow an authenticated, unprivileged local attacker to crash the system (and possibly gain higher privileges) if huge pages are enabled in the system.

A fix has been committed to upstream, commit 90481622d75715bfcb68501280a917dbfe516029 "hugepages: fix use after free bug in "quota" handling"

Version-Release number of selected component (if applicable):
The bug exists in kernel versions 2.6.24 and above.

How reproducible:
The attached tarball includes an example code which utilizes a fuse mount with O_DIRECT flag to reproduce the issue. The code will work only on kernels 2.6.32 and above since it uses the new "anonymous mapping" API for getting huge pages.  Similar reproduction is possible when using the shmem API or the hugetlbfs API.  Stock kernel might not crash, debug kernel will detect the corruption and kill the process.

Steps to Reproduce:
1. Untar the attached file
2. Run run_test.sh. The fuse-devel package and sudo rights are required for the fuse mount. Sudo rights are also required for enabling huge pages.
3. Observe the kernel crash when running debug kernel. Normal kernels will (usually) not crash, as the slab allocator will not return the memory blocks to the system general pool for a while.

Actual results:
A general protection fault message is printed, and the server is frozen.

Expected results:
The process should exit without the kernel crashing.

Additional info:
Verified on RHEL 6.0 with Dell PowerEdge 2950, should exist also on RHEL 6.2 and 6.1.

Upstream commit:
http://git.kernel.org/linus/90481622d75715bfcb68501280a917dbfe516029

Acknowledgements:

Red Hat would like to thank Shachar Raindel for reporting this issue.
Comment 2 Eugene Teo (Security Response) 2012-04-29 21:08:50 EDT
*** Bug 815065 has been marked as a duplicate of this bug. ***
Comment 3 Petr Matousek 2012-07-25 07:52:45 EDT
Statement:

This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 5. Future kernel updates for Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux MRG 2 may address this issue.
Comment 6 Petr Matousek 2012-07-25 07:55:10 EDT
Created kernel tracking bugs for this issue

Affects: fedora-all [bug 843038]
Comment 7 Frederic Weisbecker 2012-08-01 09:49:26 EDT
(In reply to comment #0)
> There is a use after free bug in the kernel hugetlb code. The bug can allow
> an authenticated, unprivileged local attacker to crash the system (and
> possibly gain higher privileges) if huge pages are enabled in the system.
> 
> A fix has been committed to upstream, commit
> 90481622d75715bfcb68501280a917dbfe516029 "hugepages: fix use after free bug
> in "quota" handling"
> 
> Version-Release number of selected component (if applicable):
> The bug exists in kernel versions 2.6.24 and above.
> 
> How reproducible:
> The attached tarball includes an example code which utilizes a fuse mount
> with O_DIRECT flag to reproduce the issue. The code will work only on
> kernels 2.6.32 and above since it uses the new "anonymous mapping" API for
> getting huge pages.  Similar reproduction is possible when using the shmem
> API or the hugetlbfs API.  Stock kernel might not crash, debug kernel will
> detect the corruption and kill the process.
> 
> Steps to Reproduce:
> 1. Untar the attached file
> 2. Run run_test.sh. The fuse-devel package and sudo rights are required for
> the fuse mount. Sudo rights are also required for enabling huge pages.
> 3. Observe the kernel crash when running debug kernel. Normal kernels will
> (usually) not crash, as the slab allocator will not return the memory blocks
> to the system general pool for a while.

Hi Eugene.

The proposed testcase seem to be missing in attachment.
Comment 8 Petr Matousek 2012-08-01 10:01:58 EDT
(In reply to comment #7)
> Hi Eugene.
> 
> The proposed testcase seem to be missing in attachment.

Please see bug 815065 comment #0
Comment 10 errata-xmlrpc 2012-11-06 13:17:41 EST
This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2012:1426 https://rhn.redhat.com/errata/RHSA-2012-1426.html
Comment 11 errata-xmlrpc 2012-12-04 14:58:13 EST
This issue has been addressed in following products:

  MRG for RHEL-6 v.2

Via RHSA-2012:1491 https://rhn.redhat.com/errata/RHSA-2012-1491.html
Comment 13 errata-xmlrpc 2013-04-16 14:33:55 EDT
This issue has been addressed in following products:

  Red Hat Enterprise Linux 6.2 EUS - Server Only

Via RHSA-2013:0741 https://rhn.redhat.com/errata/RHSA-2013-0741.html

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