---------- Forwarded message ----------
Date: Sun, 11 Aug 2002 17:09:03 -0400
From: Niels Provos <provos@citi.umich.edu>
To: security-announce@openbsd.org, announce@openbsd.org, misc@openbsd.org
Subject: OpenBSD Security Advisory: Select Boundary Condition
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OpenBSD Security Advisory (adv.select)
Original Release Date: 2002-08-11
1. Systems affected:
All versions of OpenBSD.
2. Overview:
Insufficient boundary checks in the select call allow an
attacker to overwrite kernel memory and execute arbitrary code
in kernel context.
Traditionally, the size parameter for the select system call
is a signed integer. As a result, the kernel evaluates the
upper boundary checks in a signed context, so that an attacker
can circumvent when using certain negative values.
When the kernel copies the data for the select system call
from userland the size is used as an unsigned integer which
causes kernel memory to be overwritten with arbitrary data.
2. Impact:
Local users can obtain complete system privileges and
circumvent the extra security measures provided by the
securelevel system.
3. Solution:
Apply one of the supplied kernel patches or update to
3.0-stable or 3.1-stable from 2002-08-11 17:00 EDT or later.
4. Patch:
ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.1/common/014_scarg.patch
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