Re: [PATCH 0/2] maple_tree: Fix mas_prev() state regression.

From: Liam R. Howlett
Date: Thu Sep 21 2023 - 19:52:07 EST


* Pedro Falcato <pedro.falcato@xxxxxxxxx> [230921 19:41]:
> On Fri, Sep 22, 2023 at 12:34 AM Liam R. Howlett
> <Liam.Howlett@xxxxxxxxxx> wrote:
> >
> > * Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> [230921 19:27]:
> > > On Thu, 21 Sep 2023 20:23:11 +0100 Matthew Wilcox <willy@xxxxxxxxxxxxx> 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.
> > >
> >
> > I don't think the irc channel is logged so I'll respin with a cleaner
> > changelog for both patches and the subject of patch 1.
>
> FYI:
>
> The original distro bug report: https://bugs.archlinux.org/task/79656
> The original userspace program bug report:
> https://github.com/cebix/macemu/issues/271
>
> (and yes, this is my fault, I should've raised this on the ML with the
> regression tracker and all, but I tried to write my own fix then
> realized it was trickier than it looked and pinged Liam)

No problem at all, but since the links are available I will put them
into the changelog.

Thanks,
Liam