FreeBSD Security Advisory FreeBSD-SA-06:18.ppp [REVISED]

Type securityvulns
Reporter Securityvulns
Modified 2006-08-28T00:00:00



============================================================================= FreeBSD-SA-06:08.ppp Security Advisory The FreeBSD Project

Topic: Buffer overflow in sppp(4)

Category: core Module: sys_net Announced: 2006-08-23 Credits: Martin Husemann, Pavel Cahyna Affects: All FreeBSD releases. Corrected: 2006-08-23 22:01:44 UTC (RELENG_6, 6.1-STABLE) 2006-08-23 22:02:25 UTC (RELENG_6_1, 6.1-RELEASE-p4) 2006-08-23 22:02:52 UTC (RELENG_6_0, 6.0-RELEASE-p10) 2006-08-23 22:03:55 UTC (RELENG_5, 5.5-STABLE) 2006-08-23 22:04:28 UTC (RELENG_5_5, 5.5-RELEASE-p3) 2006-08-23 22:04:58 UTC (RELENG_5_4, 5.4-RELEASE-p17) 2006-08-23 22:05:49 UTC (RELENG_5_3, 5.3-RELEASE-p32) 2006-08-23 22:06:08 UTC (RELENG_4, 4.11-STABLE) 2006-08-23 22:06:40 UTC (RELENG_4_11, 4.11-RELEASE-p20) CVE Name: CVE-2006-4304

For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:>.

  1. Revision History

v1.0 2006-08-23 Initial release. v1.1 2006-08-25 Corrected name of affected driver.

NOTE WELL: The original version of this advisory identified the affected driver as ppp(4). This is incorrect; the problem occurs in the sppp(4) driver instead.

I. Background

The sppp(4) driver implements the state machine and the Link Control Protocol (LCP) of the Point-to-Point Protocol (PPP) and is used in combination with underlying drivers which provide synchronous point-to-point connections. In particular, sppp(4) is commonly used with i4bisppp(4) and ng_sppp(4).

II. Problem Description

While processing Link Control Protocol (LCP) configuration options received from the remote host, sppp(4) fails to correctly validate option lengths. This may result in data being read or written beyond the allocated kernel memory buffer.

III. Impact

An attacker able to send LCP packets, including the remote end of a sppp(4) connection, can cause the FreeBSD kernel to panic. Such an attacker may also be able to obtain sensitive information or gain elevated privileges.

IV. Workaround

No workaround is available, but systems which do not use sppp(4) are not vulnerable.

V. Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE, 5-STABLE, or 6-STABLE, or to the RELENG_6_1, RELENG_6_0, RELENG_5_5, RELENG_5_4, RELENG_5_3, or RELENG_4_11 security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.11, 5.3, 5.4, 5.5, 6.0, and 6.1 systems.

a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility.

[FreeBSD 4.x]



[FreeBSD 5.3]



[FreeBSD 5.4, 5.5, and 6.x]



b) Apply the patch.

cd /usr/src

patch < /path/to/patch

c) Recompile your kernel as described in <URL:> and reboot the system.

VI. Correction details

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

Branch Revision Path

RELENG_4 src/sys/net/if_spppsubr.c RELENG_4_11 src/UPDATING src/sys/conf/ src/sys/net/if_spppsubr.c RELENG_5 src/sys/net/if_spppsubr.c RELENG_5_5 src/UPDATING 1.342. src/sys/conf/ src/sys/net/if_spppsubr.c RELENG_5_4 src/UPDATING 1.342. src/sys/conf/ src/sys/net/if_spppsubr.c RELENG_5_3 src/UPDATING 1.342. src/sys/conf/ src/sys/net/if_spppsubr.c RELENG_6 src/sys/net/if_spppsubr.c RELENG_6_1 src/UPDATING 1.416. src/sys/conf/ src/sys/net/if_spppsubr.c RELENG_6_0 src/UPDATING 1.416. src/sys/conf/ src/sys/net/if_spppsubr.c

VII. References

The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD)

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