Re: [PATCH] Fix root hole in pktcdvd

[Greg KH]

On Tue, May 17, 2005 at 06:00:25AM +0100, Al Viro wrote:
> On Mon, May 16, 2005 at 09:37:49PM -0700, Greg KH wrote:
> > ioctl_by_bdev may only be used INSIDE the kernel.  If the "arg" argument
> > refers to memory that is accessed by put_user/get_user in the ioctl
> > function, the memory needs to be in the kernel address space (that's the
> > set_fs(KERNEL_DS) doing in the ioctl_by_bdev).  This works on i386 because
> > even with set_fs(KERNEL_DS) the user space memory is still accessible with
> > put_user/get_user.  That is not true for s390.  In short the ioctl
> > implementation of the pktcdvd device driver is horribly broken.
> 
> Same comment as for previous patch.  I'll take a look at that sucker,
> it might happen to be OK, seeing that most of the bdev ->ioctl() instances
> ignore file argument and we might get away with passing odd stuff to
> anything that could occur here.

Ok, so, do you suggest we just pass NULL in there, or do you have a
better suggestion?

thanks,

greg k-h
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