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TITLE:
Linux Kernel Block Layer Denial of Service Vulnerabilities

SECUNIA ADVISORY ID:
SA42176

VERIFY ADVISORY:
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http://secunia.com/advisories/42176/
Customer Area (Credentials Required)
https://ca.secunia.com/?page=viewadvisory&vuln_id=42176

RELEASE DATE:
2010-11-12

DISCUSS ADVISORY:
http://secunia.com/advisories/42176/#comments

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http://secunia.com/advisories/42176/

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DESCRIPTION:
Dan Rosenberg has reported some vulnerabilities in the Linux Kernel,
which can be exploited by malicious, local users to cause a DoS
(Denial of Service).

1) Errors within the "bio_copy_user_iov()" and "__bio_map_user_iov()"
functions in fs/bio.c when calculating the number of pages to allocate
can be exploited to cause a huge allocation and e.g. trigger the out
of memory handler or crash a system by sending specially crafted
IOCTLs.

2) An error within the "blk_rq_map_user_iov()" functon in
block/blk-map.c when processing certain I/O requests with a length of
0 can be exploited to crash the system.

Successful exploitation requires that the attacker can send IOCTLs to
SCSI devices (e.g. is a member of the "cdrom" group).

SOLUTION:
Fixed in Jens Axboe's GIT repository.

PROVIDED AND/OR DISCOVERED BY:
Dan Rosenberg

ORIGINAL ADVISORY:
http://www.openwall.com/lists/oss-security/2010/11/10/18

1)
http://git.kernel.org/?p=linux/kernel/git/axboe/linux-2.6-block.git;a=commitdiff;h=cb4644cac4a2797afc847e6c92736664d4b0ea34
2)
http://git.kernel.org/?p=linux/kernel/git/axboe/linux-2.6-block.git;a=commitdiff;h=9284bcf4e335e5f18a8bc7b26461c33ab60d0689

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