linux-kernel - Re: [PATCH 1/2] topology: use bin_attribute to avoid buff overflow

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Date:   Tue, 1 Jun 2021 09:13:27 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     "Song Bao Hua (Barry Song)" <song.bao.hua@...ilicon.com>
Cc:     "tiantao (H)" <tiantao6@...ilicon.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH 1/2] topology: use bin_attribute to avoid buff overflow

On Tue, Jun 01, 2021 at 07:04:33AM +0000, Song Bao Hua (Barry Song) wrote:
> 
> 
> > -----Original Message-----
> > From: Greg KH [mailto:gregkh@...uxfoundation.org]
> > Sent: Tuesday, June 1, 2021 4:59 PM
> > To: tiantao (H) <tiantao6@...ilicon.com>
> > Cc: linux-kernel@...r.kernel.org; akpm@...ux-foundation.org; Song Bao Hua
> > (Barry Song) <song.bao.hua@...ilicon.com>; Andy Shevchenko
> > <andriy.shevchenko@...ux.intel.com>; Rafael J. Wysocki <rafael@...nel.org>
> > Subject: Re: [PATCH 1/2] topology: use bin_attribute to avoid buff overflow
> > 
> > On Tue, Jun 01, 2021 at 10:56:49AM +0800, Tian Tao wrote:
> > > Reading sys/devices/system/cpu/cpuX/topology/ returns cpu topology.
> > > However, the size of this file is limited to PAGE_SIZE because of the
> > > limitation for sysfs attribute. so we use bin_attribute instead of
> > > attribute to avoid NR_CPUS too big to cause buff overflow.
> > >
> > > This patch is based on the following discussion.
> > > https://www.spinics.net/lists/linux-doc/msg95921.html
> > 
> > Please use lore.kernel.org for links as we have no control over other
> > sites to ensure that they will work in the future.  Use the message id
> > in the link as well, so that if something were to happen to lore, we can
> > figure it out.
> > 
> > Also, you are modifying a bunch of different files here, do you mean to
> > do it for all of them?
> 
> The plan is providing a common wrapper similar with cpumap_print_to_pagebuf
> so that all modules which have bitmap and list topology ABI can move to use
> it.

Ok, then create the new function and then convert to use it, do not
bundle it together in the same patch.

thanks,

greg k-h