Re: [PATCH] input: mtk-pmic-keys: Fix probe when no DT node present

[Dmitry Torokhov]

On Fri, Jun 22, 2018 at 01:42:28PM +0200, Matthias Brugger wrote:
> The drivers gets probed from a mfd devices. So the driver runs
> probe although no DT node exists. This leads to a NULL pointer
> dereference in the probe function. Check if a node exists and
> error out in case none is present.

Hmm, if a cell specifies of_compatible and no such node is present in DT
maybe we should bail out in mfd_add_device() instead of pushing the
check into individual drivers? Something like:

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 94e3f32ce935..36a5fd98000d 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -137,6 +137,18 @@ static inline void mfd_acpi_add_device(const struct 
mfd_cell *cell,
 }
 #endif
 
+static struct device_node *mfd_get_node_for_cell(struct device *parent,
+                                                const struct mfd_cell *cell)
+{
+       struct device_node *np;
+
+       for_each_child_of_node(parent->of_node, np)
+               if (of_device_is_compatible(np, cell->of_compatible))
+                       return np;
+
+       return NULL;
+}
+
 static int mfd_add_device(struct device *parent, int id,
                          const struct mfd_cell *cell, atomic_t *usage_count,
                          struct resource *mem_base,
@@ -144,7 +156,6 @@ static int mfd_add_device(struct device *parent, int id,
 {
        struct resource *res;
        struct platform_device *pdev;
-       struct device_node *np = NULL;
        int ret = -ENOMEM;
        int platform_id;
        int r;
@@ -176,11 +187,11 @@ static int mfd_add_device(struct device *parent, int id,
                goto fail_res;
 
        if (parent->of_node && cell->of_compatible) {
-               for_each_child_of_node(parent->of_node, np) {
-                       if (of_device_is_compatible(np, cell->of_compatible)) {
-                               pdev->dev.of_node = np;
-                               break;
-                       }
+               pdev->dev.of_node = mfd_get_node_for_cell(parent, cell);
+               if (!pdev->dev.of_node) {
+                       dev_err(parent, "unable to locate node for %s (%s)\n",
+                               cell->name, cell->of_compatible);
+                       goto fail_res;
                }
        }
 
Lee?

> 
> Fixes: 3e9f0b3e2b27 ("input: Add MediaTek PMIC keys support")
> Signed-off-by: Matthias Brugger <mbrug...@suse.com>
> ---
>  drivers/input/keyboard/mtk-pmic-keys.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/input/keyboard/mtk-pmic-keys.c 
> b/drivers/input/keyboard/mtk-pmic-keys.c
> index 02c67a1749fc..388043e1939c 100644
> --- a/drivers/input/keyboard/mtk-pmic-keys.c
> +++ b/drivers/input/keyboard/mtk-pmic-keys.c
> @@ -257,6 +257,9 @@ static int mtk_pmic_keys_probe(struct platform_device 
> *pdev)
>       const struct of_device_id *of_id =
>               of_match_device(of_mtk_pmic_keys_match_tbl, &pdev->dev);
>  
> +     if (of_id == NULL)
> +             return -ENODEV;
> +
>       keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL);
>       if (!keys)
>               return -ENOMEM;
> -- 
> 2.17.1
> 

Thanks.

-- 
Dmitry