linux-kernel - Re: [PATCH 4.14 58/62] mtd: rawnand: atmel: fix OF child-node lookup

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Date:   Mon, 26 Nov 2018 10:16:01 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     Naresh Kamboju <naresh.kamboju@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux- stable <stable@...r.kernel.org>,
        nicolas.ferre@...rochip.com, rainyfeeling@...look.com,
        johan@...nel.org
Subject: Re: [PATCH 4.14 58/62] mtd: rawnand: atmel: fix OF child-node lookup

On Mon, Nov 26, 2018 at 04:08:40PM +0100, Boris Brezillon wrote:
>On Mon, 26 Nov 2018 19:46:15 +0530
>Naresh Kamboju <naresh.kamboju@...aro.org> wrote:
>
>> Do you see build failure arm x15 beagleboard on 4.14 due to this patch ?
>>
>> On Mon, 26 Nov 2018 at 16:31, Greg Kroah-Hartman
>> <gregkh@...uxfoundation.org> wrote:
>> >
>> > 4.14-stable review patch.  If anyone has any objections, please let me know.
>> >
>> > ------------------
>> >
>> > From: Johan Hovold <johan@...nel.org>
>> >
>> > commit 5d1e9c2212ea6b4dd735e4fc3dd6279a365d5d10 upstream.
>> >
>> > Use the new of_get_compatible_child() helper to lookup the nfc 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 a related nfc-node reference leak.
>> >
>> > Fixes: f88fc122cc34 ("mtd: nand: Cleanup/rework the atmel_nand driver")
>> > Cc: stable <stable@...r.kernel.org>     # 4.11
>> > Cc: Nicolas Ferre <nicolas.ferre@...rochip.com>
>> > Cc: Josh Wu <rainyfeeling@...look.com>
>> > Cc: Boris Brezillon <boris.brezillon@...tlin.com>
>> > Signed-off-by: Johan Hovold <johan@...nel.org>
>> > Signed-off-by: Boris Brezillon <boris.brezillon@...tlin.com>
>> > Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> >
>> > ---
>> >  drivers/mtd/nand/atmel/nand-controller.c |   11 +++++++----
>> >  1 file changed, 7 insertions(+), 4 deletions(-)
>> >
>> > --- a/drivers/mtd/nand/atmel/nand-controller.c
>> > +++ b/drivers/mtd/nand/atmel/nand-controller.c
>> > @@ -2077,8 +2077,7 @@ atmel_hsmc_nand_controller_legacy_init(s
>> >         int ret;
>> >
>> >         nand_np = dev->of_node;
>> > -       nfc_np = of_find_compatible_node(dev->of_node, NULL,
>> > -                                        "atmel,sama5d3-nfc");
>> > +       nfc_np = of_get_compatible_child(dev->of_node, "atmel,sama5d3-nfc");
>> >         if (!nfc_np) {
>> >                 dev_err(dev, "Could not find device node for sama5d3-nfc\n");
>> >                 return -ENODEV;
>> > @@ -2492,15 +2491,19 @@ static int atmel_nand_controller_probe(s
>> >         }
>> >
>> >         if (caps->legacy_of_bindings) {
>> > +               struct device_node *nfc_node;
>> >                 u32 ale_offs = 21;
>> >
>> >                 /*
>> >                  * If we are parsing legacy DT props and the DT contains a
>> >                  * valid NFC node, forward the request to the sama5 logic.
>> >                  */
>> > -               if (of_find_compatible_node(pdev->dev.of_node, NULL,
>> > -                                           "atmel,sama5d3-nfc"))
>> > +               nfc_node = of_get_compatible_child(pdev->dev.of_node,
>> > +                                                  "atmel,sama5d3-nfc");
>> > +               if (nfc_node) {
>> >                         caps = &atmel_sama5_nand_caps;
>> > +                       of_node_put(nfc_node);
>> > +               }
>> >
>> >                 /*
>> >                  * Even if the compatible says we are dealing with an
>> >
>> >
>>
>> /drivers/mtd/nand/atmel/nand-controller.c: In function
>> 'atmel_hsmc_nand_controller_legacy_init':
>> /drivers/mtd/nand/atmel/nand-controller.c:2080:11: error: implicit
>> declaration of function 'of_get_compatible_child'; did you mean
>> 'of_get_next_available_child'? [-Werror=implicit-function-declaration]
>>    nfc_np = of_get_compatible_child(dev->of_node, "atmel,sama5d3-nfc");
>
>Looks like of_get_compatible_child() has been introduced in 4.18, hence
>this error.
>
>Greg, can you drop this patch from 4.14.y?

Interesting, none of the kernelci builds caught this? hmm

--
Thanks,
Sasha