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 <thorpejat_private>
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