FreeBSD negative argument system call buffer overflow could return sensitive information

freebsd-negative-system-call-bo (9903) The risk level is classified as MediumMedium Risk


A vulnerability in FreeBSD could allow a local attacker to obtain sensitive information. Several system calls in FreeBSD fail to properly handle signed integers. If a local attacker calls one of the affected system calls with an overly large negative argument, the attacker could overflow a buffer and cause the kernel to return portions of kernel memory, which could include file cache and terminal buffers. An attacker could use this information to possibly obtain elevated privileges on the system.


Obtain Information


Upgrade to the latest version of FreeBSD (4.6.2-RELEASE or later) or (4.6-STABLE or later), or to the appropriate RELENG_4_6 security branch dated later than 2002-08-13, as listed in FreeBSD Security Advisory FreeBSD-SA-02:38.signed-error. See References.

— OR —

Apply the signed-error patch, as listed in FreeBSD Security Advisory FreeBSD-SA-02:38.signed-error. See References.


  • FreeBSD Security Advisory FreeBSD-SA-02:38.signed-error : Boundary checking errors involving signed integers.
  • BID-5493: FreeBSD System Call Signed Integer Buffer Overflow Vulnerability
  • CVE-2002-0973: Integer signedness error in several system calls for FreeBSD 4.6.1 RELEASE-p10 and earlier may allow attackers to access sensitive kernel memory via large negative values to the (1) accept, (2) getsockname, and (3) getpeername system calls, and the (4) vesa FBIO_GETPALETTE ioctl.
  • OSVDB ID: 6045: FreeBSD Multiple System Call Integer Signedness Memory Access

Platforms Affected:

  • FreeBSD FreeBSD 4.0
  • FreeBSD FreeBSD 4.1
  • FreeBSD FreeBSD 4.1.1
  • FreeBSD FreeBSD 4.2
  • FreeBSD FreeBSD 4.3
  • FreeBSD FreeBSD 4.4
  • FreeBSD FreeBSD 4.5
  • FreeBSD FreeBSD 4.6
  • FreeBSD FreeBSD 4.6.1


Aug 19, 2002

The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (IBM Internet Security Systems X-Force) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.

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