[kernel-hardening] Re: [RFCv2 PATCH 09/18] net: convert from atomic_t to refcount_t

From: David Windsor <dwindsor@gmail.com>
To: "kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>
Cc: Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	"Anvin, H Peter" <h.peter.anvin@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will.deacon@arm.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Hans Liljestrand <ishkamiel@gmail.com>
Subject: [kernel-hardening] Re: [RFCv2 PATCH 09/18] net: convert from atomic_t to refcount_t
Date: Thu, 19 Jan 2017 10:08:25 -0500	[thread overview]
Message-ID: <CAEXv5_i4wSg_1c_0_Dv-3Eir3Y2U=ziY8jF3yieSmRJgKMgbPQ@mail.gmail.com> (raw)
In-Reply-To: <2236FBA76BA1254E88B949DDB74E612B41C3EFCD@IRSMSX102.ger.corp.intel.com>

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It might be my mail client: Gmail won't display the entire patch inline.

On Thursday, January 19, 2017, Reshetova, Elena <elena.reshetova@intel.com>
wrote:
>> On Wed, Jan 18, 2017 at 8:11 PM, Kees Cook <keescook@chromium.org> wrote:
>> > On Wed, Jan 18, 2017 at 10:39 AM, David Windsor <dwindsor@gmail.com>
>> wrote:
>> >> The relevant part of the patch has been cut off, but it appears that
>> >> you've fixed some of the issues we identified earlier as corner cases
>> >> as to reference counting in net/.  In particular, inetpeer.c has its
>> >> own garbage collection system in place which frees shared objects when
>> >> their reference count became -1 (rather than 0).  The proposed
>> >> solution was to do a global +1 on this refcounting scheme, then
>> >> replace unsupported atomic_*() functions with appropriate refcount_*()
>> >> calls.
>> >>
>> >> When submitting this to netdev, it may make sense to separate out
>> >> these changes: first, do a global +1 (while still using atomic_t),
>> >> then convert to refcount_t.  I'm already working on this now, but I
>> >> didn't know if you wanted to follow this approach or not.
>> >
>> > David, if you've got the global +1 patches ready, let's start feeding
>> > those to netdev ASAP. We can convert them to refcount_t more easily
>> > after that.
>> >
>>
>> Alright, let me get them in order and I'll submit them to netdev.  I
>> just wanted to make sure that an alternate approach hadn't been
>> decided upon.
>>
>
> No, we haven't decided on that.
> We had only some +1s, but not for all of it, so if you have a global +1,
then it is even better!
> Then we can drop +1 parts.
>
> And what do you mean by " The relevant part of the patch has been cut off
" ? It is one huge
> patch but I got it in full mailed via list. Do you see it corrupted or?
>
> Best Regards,
> Elena
>

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