Re: BK2CVS problem

From: Scott Robert Ladd (coyote_at_coyotegulch.com)
Date: 11/06/03

  • Next message: steve_at_drifthost.com: "Re: no DRQ after issuing WRITE"
    Date:	Wed, 05 Nov 2003 23:09:24 -0500
    To: Larry McVoy <lm@bitmover.com>
    
    

    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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