linux-kernel - Re: [PATCH v2 4/9] mmc: meson-mx-sdio: fix OF child-node lookup

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Date:   Tue, 4 Sep 2018 14:54:02 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Johan Hovold <johan@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Frank Rowand <frowand.list@...il.com>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>,
        Carlo Caione <carlo@...lessm.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: Re: [PATCH v2 4/9] mmc: meson-mx-sdio: fix OF child-node lookup

On Mon, Aug 27, 2018 at 04:44:44PM +0200, Ulf Hansson wrote:
> On 27 August 2018 at 10:21, Johan Hovold <johan@...nel.org> wrote:
> > Use the new of_get_compatible_child() helper to lookup the slot child
> > node instead of using of_find_compatible_node(), which searches the
> > entire tree from a given start node and thus can return an unrelated
> > (i.e. non-child) node.
> >
> > This also addresses a potential use-after-free (e.g. after probe
> > deferral) as the tree-wide helper drops a reference to its first
> > argument (i.e. the node of the device being probed).
> >
> > While at it, also fix up the related slot-node reference leak.
> >
> > Fixes: ed80a13bb4c4 ("mmc: meson-mx-sdio: Add a driver for the Amlogic Meson8 and Meson8b SoCs")
> > Cc: stable <stable@...r.kernel.org>     # 4.15
> > Cc: Carlo Caione <carlo@...lessm.com>
> > Cc: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> > Cc: Ulf Hansson <ulf.hansson@...aro.org>
> > Acked-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> > Signed-off-by: Johan Hovold <johan@...nel.org>
> 
> Acked-by: Ulf Hansson <ulf.hansson@...aro.org>

Thanks for the ack. Rob's gotten the helper into -rc2, so feel free to
pick this one up directly to whichever mmc branch you prefer. I've been
able to trigger crashes after probe deferrals due to the use-after-free,
but this seems unlikely to be exploitable.

Thanks,
Johan