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From:   Yuanyuan Zhong <yzhong@purestorage.com>
Date:   Wed, 15 Nov 2023 14:44:04 -0800
Message-ID: <CA+AMecH1TZc3zVm0OF1VwwTBCrLp9mZnOa5zw59yr_W0WbH_uw@mail.gmail.com>
Subject: Re: [PATCH] nvme-core: remove head->effects to fix use-after-free
To:     Keith Busch <kbusch@kernel.org>
Cc:     Jens Axboe <axboe@kernel.dk>, hch@lst.de, sagi@grimberg.me,
        linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
        randyj@purestorage.com, hcoutinho@purestorage.com
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On Wed, Nov 15, 2023 at 11:55=E2=80=AFAM Keith Busch <kbusch@kernel.org> wr=
ote:
>
> On Wed, Nov 15, 2023 at 11:21:53AM -0800, Yuanyuan Zhong wrote:
> > On Wed, Nov 15, 2023 at 11:02=E2=80=AFAM Jens Axboe <axboe@kernel.dk> w=
rote:
> >
> > Do you mean something like this? If not, can you please elaborate
> > "when we need"?
> > -               struct nvme_effects_log *cel =3D xa_load(&ctrl->cels, n=
s->head->ids.csi);
> > +               struct nvme_effects_log *cel =3D (ns->head->ids.csi =3D=
=3D NVME_CSI_NVM) ?
> > +                       ctrl->effects : xa_load(&ctrl->cels, ns->head->=
ids.csi);
> > Will it be good to change ctrl->effects to ctrl->effects[3] for
> > already defined CSI?
>
> I suggest either re-assign the cached head->effects to one from a still
> live controller when current path is removed, or move the saved effects
> to the subsystem instead of the controller. All controllers in the
> subsystem should be reporting the same effects log anyway, so
Is it specified in spec that all controllers in the subsystem
should be reporting the same effects log?
> duplicating all that per-controller is kind of wasteful.