Re: BK2CVS problem

[Scott Robert Ladd <coyote@coyotegulch.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