linux-kernel - Re: Undoing module RONX protection fix

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Message-ID: <87hb9hd5zn.fsf@rustcorp.com.au>
Date:	Fri, 29 Apr 2011 14:11:16 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Jan Glauber <jang@...ux.vnet.ibm.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, castet.matthieu@...e.fr,
	sliakh.lkml@...il.com, jiang@...ncsu.edu, mingo@...e.hu
Subject: Re: Undoing module RONX protection fix

On Thu, 28 Apr 2011 15:43:21 +0200, Jan Glauber <jang@...ux.vnet.ibm.com> wrote:
> On Thu, Apr 28, 2011 at 09:06:39PM +0930, Rusty Russell wrote:
> > On Thu, 28 Apr 2011 12:08:20 +0200, Jan Glauber <jang@...ux.vnet.ibm.com> wrote:
> > > How about this?
> > > 
> > > To be honest I don't like the inverse naming like in unset no-execute
> > > too much, it makes me feel dizzy. But I wanted to keep the changes
> > > minimal.
> > 
> > Yes, it should probably just be called protect_module_pages and
> > unprotect_module_pages.  The current names provide far too much
> > information.
> > 
> > But going back a bit, how did we end up with a NULL mod->module_init and
> > yet module->init_text_size, mod->init_size or mod->init_ro_size
> > non-zero?
> 
> printk'ing this reveals that mod->init_ro_size is not 0 but 0x1000.
> Therefore the first page was modified.
> 
> Looks like init_ro_size is missing the reset to zero at the end of the init_module
> syscall. Next patch ? ;-

Yes, that seems like a much cleaner and clearer fix to me...

Thanks,
Rusty.
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