Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.31 as permitted sender) client-ip=23.128.96.31;
Date:   Thu, 21 Sep 2023 16:27:48 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        maple-tree@lists.infradead.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, pedro.falcato@gmail.com,
        stable <stable@kernel.org>
Subject: Re: [PATCH 0/2] maple_tree: Fix mas_prev() state regression.
Message-Id: <20230921162748.a85eb5af766e0662e4f22a5e@linux-foundation.org>
In-Reply-To: <ZQyYH+5pnDc1KYj0@casper.infradead.org>
References: <20230921181236.509072-1-Liam.Howlett@oracle.com>
        <20230921112521.fc07c658804f4e188179da77@linux-foundation.org>
        <20230921185330.j5jw3oms4tc6crkf@revolver>
        <ZQyYH+5pnDc1KYj0@casper.infradead.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Thu, 21 Sep 2023 20:23:11 +0100 Matthew Wilcox <willy@infradead.org> wrote:

> > > It isn't clear what are the user-visible effects of this flaw?  Please
> > > send this along and I'll paste it in.
> > 
> > 
> > User may notice that mas_prev() or mas_next() calls that result in going
> > outside of the limit passed to the call will cause incorrect returns on
> > subsequent calls using that maple state, such as mas_find() skipping an
> > entry.
> 
> When Andrew says "User visible" he means "userspace visible".  Not
> "in kernel user visible".  What are the _consequences_.

Thanks ;)

We have a Link:
(https://gist.github.com/heatd/85d2971fae1501b55b6ea401fbbe485b) but it
takes us to the reproducer code.  If it took us to Pedro's initial bug
report then the sun would shine and birds would sing.