2023-09-22 00:31:48

by Andrew Morton

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

On Thu, 21 Sep 2023 20:23:11 +0100 Matthew Wilcox <[email protected]> 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.




2023-09-22 00:57:45

by Liam R. Howlett

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

* Andrew Morton <[email protected]> [230921 19:27]:
> On Thu, 21 Sep 2023 20:23:11 +0100 Matthew Wilcox <[email protected]> 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.

Thanks,
Liam

2023-09-22 01:08:11

by Pedro Falcato

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

On Fri, Sep 22, 2023 at 12:34 AM Liam R. Howlett
<[email protected]> wrote:
>
> * Andrew Morton <[email protected]> [230921 19:27]:
> > On Thu, 21 Sep 2023 20:23:11 +0100 Matthew Wilcox <[email protected]> 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)

--
Pedro

2023-09-22 08:45:59

by Liam R. Howlett

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

* Pedro Falcato <[email protected]> [230921 19:41]:
> On Fri, Sep 22, 2023 at 12:34 AM Liam R. Howlett
> <[email protected]> wrote:
> >
> > * Andrew Morton <[email protected]> [230921 19:27]:
> > > On Thu, 21 Sep 2023 20:23:11 +0100 Matthew Wilcox <[email protected]> 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