oss-security - CVE request -- kernel: proc: signedness issue in next

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Date: Tue, 19 Apr 2011 07:54:37 -0400 (EDT)
From: Petr Matousek <pmatouse@...hat.com>
To: oss-security@...ts.openwall.com
Cc: coley@...us.mitre.org, robert@...ecki.net
Subject: CVE request -- kernel: proc: signedness issue in next_pidmap()

"A signedness issue has been found in next_pidmap() function when the "last"
parameter is negative as next_pidmap() just quietly accepted whatever
"last" pid that was passed in, which is not all that safe when one of the
users is /proc.

Setting f_pos to negative value when accessing /proc via readdir()/getdents()
resulted in sign extension of this value when map pointer was being
constructed.

This later lead to #GP because the final pointer was not canonical (x86_64)."

References:
https://bugzilla.redhat.com/show_bug.cgi?id=697822
http://groups.google.com/group/fa.linux.kernel/browse_thread/thread/93c1088451fd3522/4a28ecb7f755a88d?#4a28ecb7f755a88d

Upstream commit:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=c78193e9
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=d8bdc59f

Thanks,
--
Petr Matousek / Red Hat Security Response Team

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