linux-kernel - Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return functions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sat, 2 Sep 2017 00:03:46 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-afs@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 02/11] refcount: Implement inc/decrement-and-return
 functions

On Fri, Sep 01, 2017 at 11:50:03PM +0200, Peter Zijlstra wrote:
> > Did you read the other other part of the description?
> > 
> > 	Further, both functions can be used to accurately trace the refcount
> > 	(refcount_inc() followed by refcount_read() can't be considered
> > 	accurate).
> 
> I must admit to having overlooked that. But can we treat the two issues
> separately? They are quite distinct.

So for tracing purposes inc_return/dec_return don't cover the full set.

In particular: inc_not_zero, dec_not_one and dec_and_*lock are not
covered.

dec_if_one I suppose we only care about the success case, in which case
we knew it was one by inference.