On Thu, Jun 14, 2001 at 07:09:31PM +0200, Przemyslaw Frasunek wrote:
> On Thu, Jun 14, 2001 at 05:14:46PM +0300, Georgi Guninski wrote:
> > OpenBSD 2.9,2.8
> > Have not tested on other OSes but they may be vulnerable
>
> FreeBSD 4.3-STABLE isn't vulnerable. Looks like it's dropping set[ug]id
> privileges before allowing detach.
Uh, the fundamental problem is that there's a chance to PT_ATTACH to
such a process before the P_SUGID bit is set in the proc. This can
happen when, e.g. the ucred structure is copied (there is a potentially
blocking malloc() call in that path).
A cursory glance shows several places where the FreeBSD kernel has
code like:
/* sanity check */
/* blocking call */
/* change user/group ID */
/* set P_SUGID */
During the /* blocking call */, another process can sneak in and PT_ATTACH
the process that is about to become sugid.
--
-- Jason R. Thorpe <[EMAIL PROTECTED]>
