From: Peter Hurley <peter@hurleysoftware.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Josh Triplett <josh@joshtriplett.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Fengguang Wu <fengguang.wu@intel.com>,
Iulia Manda <iulia.manda21@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Fabian Frederick <fabf@skynet.be>,
Linux Memory Management List <linux-mm@kvack.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] devpts: If initialization failed, don't crash when opening /dev/ptmx
Date: Thu, 07 May 2015 19:24:08 -0400 [thread overview]
Message-ID: <554BF418.5080200@hurleysoftware.com> (raw)
In-Reply-To: <20150507155919.16ab7177e4956d8f47803750@linux-foundation.org>
On 05/07/2015 06:59 PM, Andrew Morton wrote:
> On Wed, 6 May 2015 17:35:47 -0700 Josh Triplett <josh@joshtriplett.org> wrote:
>
>> If devpts failed to initialize, it would store an ERR_PTR in the global
>> devpts_mnt. A subsequent open of /dev/ptmx would call devpts_new_index,
>> which would dereference devpts_mnt and crash.
>>
>> Avoid storing invalid values in devpts_mnt; leave it NULL instead.
>> Make both devpts_new_index and devpts_pty_new fail gracefully with
>> ENODEV in that case, which then becomes the return value to the
>> userspace open call on /dev/ptmx.
>
> It looks like the system is pretty crippled if init_devptr_fs() fails.
> Can the user actually get access to consoles and do useful things in
> this situation? Maybe it would be better to just give up and panic?
A single-user console is definitely reachable without devpts.
>From there, one could fixup to a not-broken kernel.
Regards,
Peter Hurley
PS - But I saw you already added these to -mm
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next prev parent reply other threads:[~2015-05-07 23:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 0:35 [PATCH] devpts: If initialization failed, don't crash when opening /dev/ptmx Josh Triplett
2015-05-07 17:52 ` Peter Hurley
2015-05-07 18:34 ` josh
2015-05-07 19:26 ` [PATCHv2] " Josh Triplett
2015-05-07 22:59 ` [PATCH] " Andrew Morton
2015-05-07 23:24 ` Peter Hurley [this message]
2015-05-08 0:37 ` josh
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