Re: [security] Race condition in udev

[Scott James Remnant <scott@canonical.com>]

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On Tue, 2009-08-25 at 15:11 +0200, Florian Zumbiehl wrote:

> > > well, in those two cases always rename()ing the new node into place would
> > > work, too!? That would be a different strategy than what's in
> > > place at the moment, but it wouldn't need a special case!?
> > > 
> > The rename() will fail.
> 
> Because?
> 
POSIX.

> > > > Or when racing with devmapper which creates /dev/mapper/foo devices at
> > > > basically the same time as udev.
> > > 
> > > Seriously? How is a piece of code that does the existence check and
> > > the subsequent action depending on the result of that check non-atomically
> > > supposed to help avoid some race condition resulting from possible
> > > concurrent creation of a device node?!
> > > 
> > Read the code and find out.  It works.
> 
> Guess how I found out that it can not work.
> 
I don't know, you haven't given any detail of any problems you've
encountered.

Scott
-- 
Scott James Remnant
scott@canonical.com

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