Re: BK2CVS problem

[Scott Robert Ladd]

Larry McVoy wrote:
> On Wed, Nov 05, 2003 at 04:48:09PM -0600, Chad Kitching wrote:
>
> > From: Zwane Mwaikambo
> >
> > > > +       if ((options == (__WCLONE|__WALL)) && (current->uid = 0))
> > > > +                       retval = -EINVAL;
> > >
> > > That looks odd
> >
> > Setting current->uid to zero when options __WCLONE and __WALL are set?  The 
> > retval is dead code because of the next line, but it looks like an attempt
> > to backdoor the kernel, does it not?
>
>
> It sure does.  Note "current->uid = 0", not "current->uid == 0". 
> Good eyes, I missed that.  This function is sys_wait4() so by passing in
> __WCLONE|__WALL you are root.  How nice.

In other words, the theoretical exploit was inserted by someone clever. 
Do we have any idea who?

BTW, good job catching the problem Larry.


--
Scott Robert Ladd
Coyote Gulch Productions (http://www.coyotegulch.com)
Software Invention for High-Performance Computing

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