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From: Petr Mladek <pmladek@suse.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Helge Deller <deller@gmx.de>,
	James Bottomley <James.Bottomley@HansenPartnership.com>,
	linux-parisc@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v1] parisc: Use for_each_console() helper
Date: Thu, 30 Jan 2020 15:07:49 +0100	[thread overview]
Message-ID: <20200130140748.ugetnys4vabf6vqx@pathway.suse.cz> (raw)
In-Reply-To: <20200127094722.GU32742@smile.fi.intel.com>

On Mon 2020-01-27 11:47:22, Andy Shevchenko wrote:
> On Mon, Jan 27, 2020 at 09:48:58AM +0100, Helge Deller wrote:
> > On 25.01.20 11:25, Andy Shevchenko wrote:
> > > On Fri, Jan 24, 2020 at 09:59:48AM -0800, James Bottomley wrote:
> 
> ...
> 
> > > By the way, consider this code from register_console()
> > >
> > >   for_each_console(bcon)
> > >     if (bcon->flags & CON_BOOT)
> > >       unregister_console(bcon);
> > >
> > > It works based on assumption that next pointer of the just unregistered console
> > > is not damaged. So, My initial patch will work in the same way.
> > 
> > Yeah, but that's a typical use-after-free issue, which I wouldn't count on.
> 
> I think here is misinterpretation, i.e. unregister != free.
> Entire console code is written in the assumption that console is not being
> freed when unregistered.

Honestly, I am not sure if this is true for all console drivers
and if it is by design.

I would prefer to stay on the safe side and keep the original
code. Hotplug practices are more and more popular as everything
gets virtualized.

Best Regards,
Petr

      reply	other threads:[~2020-01-30 14:07 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-24 16:07 [PATCH v1] parisc: Use for_each_console() helper Andy Shevchenko
2020-01-24 16:39 ` James Bottomley
2020-01-24 17:38   ` Andy Shevchenko
2020-01-24 17:59     ` James Bottomley
2020-01-25 10:25       ` Andy Shevchenko
2020-01-27  8:48         ` Helge Deller
2020-01-27  9:47           ` Andy Shevchenko
2020-01-30 14:07             ` Petr Mladek [this message]

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