Bug 796829 - (CVE-2012-0879) CVE-2012-0879 kernel: block: CLONE_IO io_context refcounting issues
CVE-2012-0879 kernel: block: CLONE_IO io_context refcounting issues
Status: NEW
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=20091204,repor...
: Security
Depends On: 791125 796846
Blocks: 796839
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Reported: 2012-02-23 13:05 EST by Petr Matousek
Modified: 2015-08-02 20:03 EDT (History)
21 users (show)

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RHEL 7.3 requirements from Atomic Host:


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Description Petr Matousek 2012-02-23 13:05:09 EST
With CLONE_IO, copy_io() increments both ioc->refcount and ioc->nr_tasks. However exit_io_context() only decrements ioc->refcount if ioc->nr_tasks reaches 0.

With CLONE_IO, parent's io_context->nr_tasks is incremented, but never decremented whenever copy_process() fails afterwards, which prevents xit_io_context() from calling IO schedulers exit functions.

An unprivileged local user could use these flaws cause denial of service.

Upstream fixes:
http://git.kernel.org/linus/61cc74fbb87af6aa551a06a370590c9bc07e29d9
http://git.kernel.org/linus/b69f2292063d2caf37ca9aec7d63ded203701bf3

References:
http://comments.gmane.org/gmane.linux.kernel/922519
Comment 3 Petr Matousek 2012-02-23 13:40:22 EST
Statement:

This issue affects the Linux kernel as shipped with Red Hat Enterprise Linux 6. This issue does not affect the Linux kernel as shipped with Red Hat Enterprise Linux 4 and 5 as they did not provide support for CLONE_IO. This issue does not affect the Linux kernel as shipped with Red Hat Enterprise MRG as they already contain the fix. This has been addressed in Red Hat Enterprise Linux 6 via https://rhn.redhat.com/errata/RHSA-2012-0481.html.
Comment 4 Kurt Seifried 2012-02-23 16:49:26 EST
Added CVE as per http://www.openwall.com/lists/oss-security/2012/02/23/5
Comment 5 errata-xmlrpc 2012-04-17 14:56:35 EDT
This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2012:0481 https://rhn.redhat.com/errata/RHSA-2012-0481.html

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