Bug 538734 - (CVE-2009-4021) CVE-2009-4021 kernel: fuse: prevent fuse_put_request on invalid pointer
CVE-2009-4021 kernel: fuse: prevent fuse_put_request on invalid pointer
Status: CLOSED ERRATA
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
high Severity high
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Assigned To: Red Hat Product Security
impact=important,reported=20091119,pu...
: Security
Depends On: 538735 538736 538737
Blocks:
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Reported: 2009-11-19 04:02 EST by Eugene Teo (Security Response)
Modified: 2015-02-16 10:53 EST (History)
12 users (show)

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Doc Type: Bug Fix
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Last Closed: 2010-12-21 17:04:09 EST
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RHEL 7.3 requirements from Atomic Host:
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Description Eugene Teo (Security Response) 2009-11-19 04:02:33 EST
Description of problem:
fuse_direct_io() has a loop where requests are allocated in each iteration. if allocation fails, the loop is broken out and follows into an unconditional fuse_put_request() on that invalid pointer."

Upstream commit:
http://git.kernel.org/linus/f60311d5f7670d9539b424e4ed8b5c0872fc9e83

This can be triggered when the system is low on memory, and when the fuse_request_alloc() function called from fuse_get_req() fails. The fuse_put_request() function will then dereference the invalid pointer returned, resulting in a kernel oops.

This was introduced in 413ef8cb (v2.6.14-rc1) and fixed in v2.6.32-rc7.
Comment 2 Jan Lieskovsky 2009-11-25 11:55:30 EST
Mitre's CVE-2009-4021 entry:
----------------------------

The fuse_direct_io function in fs/fuse/file.c in the fuse subsystem in
the Linux kernel before 2.6.32-rc7 might allow attackers to cause a
denial of service (invalid pointer dereference and OOPS) via vectors
possibly related to a memory-consumption attack.
Comment 3 errata-xmlrpc 2010-01-19 18:36:53 EST
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5

Via RHSA-2010:0046 https://rhn.redhat.com/errata/RHSA-2010-0046.html
Comment 4 errata-xmlrpc 2010-01-21 09:10:40 EST
This issue has been addressed in following products:

  MRG for RHEL-5

Via RHSA-2010:0041 https://rhn.redhat.com/errata/RHSA-2010-0041.html

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