Dziura we FreeBSD

Kolejna dziura we FreeBSD.... Jak zwykle zalecany jest upgrade do najnowszej wersji, czyli w tym wypadku 4.6.1-RELEASE-p11, 4.5-RELEASE-p19 bądź 4.4-RELEASE-p26, oczywiście w zależności od posiadanego systemu. Jednakże, wydaje się, że dziura jest mało groźna. Informacja o błędzie poniżej:


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FreeBSD-SA-02:38.signed-error
Security Advisory
The FreeBSD Project

Topic: Boundary checking errors involving signed integers

Category: core
Module: sys
Announced: 2002-08-19
Credits: Silvio Cesare
Affects: All releases of FreeBSD up to and including 4.6.1-RELEASE-p10
Corrected: 2002-08-13 02:42:32 UTC (RELENG_4)
2002-08-13 12:12:36 UTC (RELENG_4_6)
2002-08-13 12:13:05 UTC (RELENG_4_5)
2002-08-13 12:13:49 UTC (RELENG_4_4)
FreeBSD only: YES

I. Background

The issue described in this advisory affects the accept(2), getsockname(2), and getpeername(2) system calls, and the vesa(4) FBIO_GETPALETTE ioctl(2).

II. Problem Description

A few system calls were identified that contained assumptions that a given argument was always a positive integer, while in fact the argument was handled as a signed integer. As a result, the boundary checking code would fail if the system call were entered with a negative argument.

III. Impact

The affected system calls could be called with large negative arguments, causing the kernel to return a large portion of kernel memory. Such memory might contain sensitive information, such as portions of the file cache or terminal buffers. This information might be directly useful, or it might be leveraged to obtain elevated privileges in some way. For example, a terminal buffer might include a user-entered password.

IV. Workaround

None.

V. Solution

1) Upgrade your vulnerable system to 4.6.2-RELEASE or 4.6-STABLE;
or to any of the RELENG_4_6 (4.6.1-RELEASE-p11), RELENG_4_5
(4.5-RELEASE-p19), or RELENG_4_4 (4.4-RELEASE-p26) security branches
dated after the respective correction dates.

2) To patch your present system:

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility. The following patch has been tested to apply to all FreeBSD 4.x releases.

# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:38/signed-error.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:38/signed-error.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in

and reboot the system.

VI. Correction details

The following list contains the revision numbers of each file that was corrected in FreeBSD.

Path Revision Branch
- -------------------------------------------------------------------------
src/sys/i386/isa/vesa.c
RELENG_4 1.32.2.1
RELENG_4_6 1.32.10.1
RELENG_4_5 1.32.8.1
RELENG_4_4 1.32.6.1
src/sys/kern/uipc_syscalls.c
RELENG_4 1.65.2.12
RELENG_4_6 1.65.2.9.6.1
RELENG_4_5 1.65.2.9.4.1
RELENG_4_4 1.65.2.9.2.1
src/sys/conf/newvers.sh
RELENG_4_6 1.44.2.23.2.16
RELENG_4_5 1.44.2.20.2.20
RELENG_4_4 1.44.2.17.2.25
- -------------------------------------------------------------------------