linux-kernel - Re: [PATCH] platform/x86: wmi: Do not mix pages and kmalloc

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Message-ID: <1533555392.28014.25.camel@gmail.com>
Date:   Mon, 06 Aug 2018 14:36:32 +0300
From:   Mihai Donțu <mihai.dontu@...il.com>
To:     Darren Hart <dvhart@...radead.org>
Cc:     keescook@...omium.org, linux-kernel@...r.kernel.org,
        andy@...radead.org, platform-driver-x86@...r.kernel.org,
        Mario.Limonciello@...l.com
Subject: Re: [PATCH] platform/x86: wmi: Do not mix pages and kmalloc

Hi Darren,

On Fri, 2018-06-22 at 16:27 -0700, Darren Hart wrote:
> On Thu, Jun 21, 2018 at 01:24:34AM +0000, Mario.Limonciello@...l.com wrote:
> > > -----Original Message-----
> > > From: Darren Hart [mailto:dvhart@...radead.org]
> > > Sent: Wednesday, June 20, 2018 7:17 PM
> > > To: Kees Cook
> > > Cc: LKML; Andy Shevchenko; Platform Driver; Mihai Donțu; Limonciello, Mario
> > > Subject: Re: [PATCH] platform/x86: wmi: Do not mix pages and kmalloc
> > > 
> > > On Wed, Jun 20, 2018 at 04:43:14PM -0700, Kees Cook wrote:
> > > > On Wed, Jun 20, 2018 at 4:37 PM, Darren Hart <dvhart@...radead.org> wrote:
> > > > > On Wed, Jun 20, 2018 at 02:31:41PM -0700, Kees Cook wrote:
> > > > > > The probe handler_data was being allocated with __get_free_pages()
> > > > > > for no reason I could find. The error path was using kfree(). Since
> > > > > 
> > > > > v4 of Mario's series used kmalloc:
> > > > > https://patchwork.kernel.org/patch/9985827/
> > > > > 
> > > > > This was changed in v10 to use __get_free_pages:
> > > > > https://patchwork.kernel.org/patch/10018023/
> > > > > 
> > > > > But... I'm not finding the discussion that led to this change.... Mario,
> > > > > do you recall? Something about contiguous memory? We had a similar
> > > > > discussion on an earlier series:
> > > > > 
> > > > > https://patchwork.kernel.org/patch/9975277/
> > > > 
> > > > FWIW, kmalloc gets you contiguous memory...
> > > 
> > > Yeah, I'm not finding a valid reason to use __get_free_pages over kmalloc in
> > > this case. I'll give Mario a chance to respond in case I'm just missing
> > > something, but otherwise will plan to apply this patch.
> > 
> > I think it was for contiguous memory, so if kmalloc is giving that I agree
> > no need to keep __get_free_pages instead.
> > 
> > Acked-by: Mario Limonciello <Mario.limonciello@...l.com>
> 
> Confirmed, kmalloc in physically contiguous.
> 
> Queued up, and tagged for stable. Thanks everyone.
> 

Would it be possible to queue this for 4.18 or is it too late? I just
noticed it has not reached 4.17.12 either.

Thanks,

-- 
Mihai Donțu