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SubjectRe: [PATCH v2 5/9] mtd: nand: atmel: fix OF child-node lookup
Hi Johan

On Mon, 27 Aug 2018 10:21:49 +0200
Johan Hovold <johan@kernel.org> wrote:

> 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@vger.kernel.org> # 4.11
> Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
> Cc: Josh Wu <rainyfeeling@outlook.com>
> Cc: Boris Brezillon <boris.brezillon@bootlin.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Acked-by: Boris Brezillon <boris.brezillon@bootlin.com>

I'll let Miquel queue this patch to the nand/next branch, unless you
want it to be merged in 4.19, in which case I'll queue it to the
mtd/fixes branch.

Thanks,

Boris

> ---
> drivers/mtd/nand/raw/atmel/nand-controller.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/atmel/nand-controller.c b/drivers/mtd/nand/raw/atmel/nand-controller.c
> index a068b214ebaa..d3dfe63956ac 100644
> --- a/drivers/mtd/nand/raw/atmel/nand-controller.c
> +++ b/drivers/mtd/nand/raw/atmel/nand-controller.c
> @@ -2061,8 +2061,7 @@ atmel_hsmc_nand_controller_legacy_init(struct atmel_hsmc_nand_controller *nc)
> 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");
>
> nc->clk = of_clk_get(nfc_np, 0);
> if (IS_ERR(nc->clk)) {
> @@ -2472,15 +2471,19 @@ static int atmel_nand_controller_probe(struct platform_device *pdev)
> }
>
> 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

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