From owner-freebsd-announce Tue Jan 7 9:49:13 2003 Delivered-To: freebsd-announce@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 15CFF37B405; Tue, 7 Jan 2003 09:49:10 -0800 (PST) Received: from freefall.freebsd.org (freefall.freebsd.org [216.136.204.21]) by mx1.FreeBSD.org (Postfix) with ESMTP id 24FA643EB2; Tue, 7 Jan 2003 09:49:08 -0800 (PST) (envelope-from security-advisories@freebsd.org) Received: from freefall.freebsd.org (nectar@localhost [127.0.0.1]) by freefall.freebsd.org (8.12.6/8.12.6) with ESMTP id h07Hn8NS058200; Tue, 7 Jan 2003 09:49:08 -0800 (PST) (envelope-from security-advisories@freebsd.org) Received: (from nectar@localhost) by freefall.freebsd.org (8.12.6/8.12.6/Submit) id h07Hn85x058198; Tue, 7 Jan 2003 09:49:08 -0800 (PST) Date: Tue, 7 Jan 2003 09:49:08 -0800 (PST) Message-Id: <200301071749.h07Hn85x058198@freefall.freebsd.org> X-Authentication-Warning: freefall.freebsd.org: nectar set sender to security-advisories@freebsd.org using -f From: FreeBSD Security Advisories To: FreeBSD Security Advisories Subject: FreeBSD Security Advisory FreeBSD-SA-02:44.filedesc Reply-To: security-advisories@freebsd.org Sender: owner-freebsd-announce@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-02:44.filedesc Security Advisory The FreeBSD Project Topic: file descriptor leak in fpathconf Category: core Module: kernel Announced: 2003-01-07 Credits: Joost Pol Affects: FreeBSD 4.3-RELEASE and later versions Corrected: 2002-11-11 01:43:31 UTC (RELENG_4) 2003-01-06 12:37:52 UTC (RELENG_4_7) 2003-01-06 12:38:21 UTC (RELENG_4_6) 2003-01-07 15:17:16 UTC (RELENG_4_5) 2003-01-07 15:17:40 UTC (RELENG_4_4) 2003-01-06 21:20:54 UTC (RELENG_5_0) FreeBSD only: YES 0. Revision History 2003-01-06 v1.0 Initial release. 2003-01-07 v1.1 Added information regarding bug in FreeBSD 5.x. Added correction details for RELENG_4_5, RELENG_4_4. I. Background The fpathconf system call provides a method for applications to determine the current value of a configurable system limit or option variable associated with a pathname or file descriptor. II. Problem Description A programming error in the fpathconf system call can result in the given file descriptor's reference count being erroneously incremented. A similar problem exists in the developer preview versions of FreeBSD 5.0, affecting the lseek(2), dup(2), and other system calls. III. Impact A local attacker may cause the operating system to crash by repeatedly calling fpathconf on a file descriptor until the reference count wraps to a negative value, and then calling close on that file descriptor. Similarly, it may be possible to cause a file descriptor to reference unallocated kernel memory, but remain valid. If a new file is later opened and the kernel allocates the new file structure at the same memory location, then an attacker may be able to gain read or write access to that file. This may in turn lead to privilege escalation. IV. Workaround There is no workaround. V. Solution The following patch has been verified to apply to FreeBSD 4.4, 4.5, 4.6, and 4.7 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:44/filedesc.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:44/filedesc.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/kern/kern_descrip.c RELENG_4 1.81.2.15 RELENG_4_7 1.81.2.14.4.1 RELENG_4_6 1.81.2.14.2.1 RELENG_4_5 1.81.2.9.2.3 RELENG_4_4 1.81.2.8.2.3 RELENG_5_0 1.169.2.2 src/sys/kern/vfs_syscalls.c RELENG_5_0 1.297.2.2 - ------------------------------------------------------------------------- VII. References -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (FreeBSD) iD8DBQE+GxDCFdaIBMps37IRAkDtAJ9Ma79bfwhHHBMe1v0gVgvzrFtoMgCgmh/v iyuKtTozFxmSATQP1w5VEWg= =MWcN -----END PGP SIGNATURE----- This is the moderated mailing list freebsd-announce. The list contains announcements of new FreeBSD capabilities, important events and project milestones. See also the FreeBSD Web pages at http://www.freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-announce" in the body of the message