From: Peter Zijlstra <peterz@infradead.org>
To: "Reshetova, Elena" <elena.reshetova@intel.com>
Cc: "kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Greg KH <gregkh@linuxfoundation.org>,
Kees Cook <keescook@chromium.org>,
"will.deacon@arm.com" <will.deacon@arm.com>,
Boqun Feng <boqun.feng@gmail.com>,
Hans Liljestrand <ishkamiel@gmail.com>,
David Windsor <dwindsor@gmail.com>,
aik@ozlabs.ru, david@gibson.dropbear.id.au
Subject: [kernel-hardening] Re: Conversion from atomic_t to refcount_t: summary of issues
Date: Mon, 28 Nov 2016 13:44:40 +0100 [thread overview]
Message-ID: <20161128124440.GK3174@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161128121347.GY3092@twins.programming.kicks-ass.net>
On Mon, Nov 28, 2016 at 01:13:47PM +0100, Peter Zijlstra wrote:
> On Mon, Nov 28, 2016 at 11:56:17AM +0000, Reshetova, Elena wrote:
> > - if (atomic_cmpxchg(&p->refcnt, 0, -1) == 0) {..} (typical for networking code)
>
> That's really weird, a refcount of -1 doesn't really make sense.
I looked at the one in inetpeer.c, and I think we can simply do +1 on
the entire refcount scheme and it'll work.
There is no dec_and_test anywhere, the only one doing deletion is that
GC. If that were to do dec_if_one(), then lookup_rcu() can do the normal
inc_not_zero().
next prev parent reply other threads:[~2016-11-28 12:44 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-28 11:56 [kernel-hardening] Conversion from atomic_t to refcount_t: summary of issues Reshetova, Elena
2016-11-28 12:13 ` [kernel-hardening] " Peter Zijlstra
2016-11-28 12:44 ` Peter Zijlstra [this message]
2016-11-28 12:48 ` Peter Zijlstra
2016-11-28 14:12 ` [kernel-hardening] " Reshetova, Elena
2016-11-29 3:19 ` [kernel-hardening] " Alexey Kardashevskiy
2016-11-29 9:31 ` Peter Zijlstra
2016-11-30 0:23 ` Alexey Kardashevskiy
2016-11-29 15:35 ` [kernel-hardening] " Reshetova, Elena
2016-11-29 15:47 ` Peter Zijlstra
2016-12-01 19:15 ` [kernel-hardening] " Peter Zijlstra
2016-12-01 21:31 ` David Windsor
2016-12-01 23:03 ` Peter Zijlstra
2016-12-01 23:20 ` Kees Cook
2016-12-01 23:29 ` David Windsor
2016-12-02 1:17 ` Boqun Feng
2016-12-02 20:25 ` David Windsor
2016-12-07 13:24 ` Peter Zijlstra
2016-12-07 19:03 ` David Windsor
2016-12-09 14:48 ` David Windsor
2016-12-07 13:36 ` Peter Zijlstra
2016-12-01 23:20 ` David Windsor
2016-12-07 13:21 ` Peter Zijlstra
2016-12-02 15:44 ` Liljestrand Hans
2016-12-02 16:14 ` Greg KH
2016-12-07 13:52 ` Peter Zijlstra
2016-12-07 15:59 ` David Windsor
2016-12-07 16:26 ` Peter Zijlstra
2016-12-07 16:31 ` David Windsor
2016-12-16 12:10 ` [kernel-hardening] " Reshetova, Elena
2016-12-16 14:01 ` [kernel-hardening] " Peter Zijlstra
2016-12-19 7:55 ` [kernel-hardening] " Reshetova, Elena
2016-12-19 10:12 ` [kernel-hardening] " Peter Zijlstra
2016-12-20 9:13 ` [kernel-hardening] " Reshetova, Elena
2016-12-20 9:30 ` [kernel-hardening] " Greg KH
2016-12-20 9:40 ` [kernel-hardening] " Reshetova, Elena
2016-12-20 9:51 ` [kernel-hardening] " Greg KH
2016-12-20 9:55 ` [kernel-hardening] " Reshetova, Elena
2016-12-20 10:26 ` [kernel-hardening] " Greg KH
2016-12-20 9:41 ` Peter Zijlstra
2016-12-20 9:58 ` [kernel-hardening] " Reshetova, Elena
2016-12-20 10:55 ` [kernel-hardening] " Liljestrand Hans
2016-12-20 13:13 ` Peter Zijlstra
2016-12-20 13:35 ` Reshetova, Elena
2016-12-20 15:20 ` Liljestrand Hans
2016-12-20 15:52 ` Peter Zijlstra
2017-01-10 14:58 ` Peter Zijlstra
2016-12-07 14:13 ` Peter Zijlstra
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