diff mbox series

[v6,1/2] iio: sx9310: Fix access to variable DT array

Message ID 20210322073220.1637117-2-gwendal@chromium.org (mailing list archive)
State New
Headers show
Series iio: sx9310: Support ACPI properties | expand

Commit Message

Gwendal Grignou March 22, 2021, 7:32 a.m. UTC
With the current code, we want to read 4 entries from DT array
"semtech,combined-sensors". If there are less, we silently fail as
of_property_read_u32_array() returns -EOVERFLOW.

First count the number of entries and if between 1 and 4, collect the
content of the array.

Fixes: 5b19ca2c78a0 ("iio: sx9310: Set various settings from DT")
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
---
 Changes in v6:
 Fix error in of_property_count_elems_of_size() argumnent:
 Used ARRAY_SIZE(combined) [4] instead of sizeof(u32).

 Changes in v5:
 new, split fixes from changes needed for ACPI support.

 drivers/iio/proximity/sx9310.c | 40 ++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 12 deletions(-)

Comments

Alexandru Ardelean March 22, 2021, 11:16 a.m. UTC | #1
On Mon, Mar 22, 2021 at 9:33 AM Gwendal Grignou <gwendal@chromium.org> wrote:
>
> With the current code, we want to read 4 entries from DT array
> "semtech,combined-sensors". If there are less, we silently fail as
> of_property_read_u32_array() returns -EOVERFLOW.
>
> First count the number of entries and if between 1 and 4, collect the
> content of the array.
>
> Fixes: 5b19ca2c78a0 ("iio: sx9310: Set various settings from DT")
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> ---
>  Changes in v6:
>  Fix error in of_property_count_elems_of_size() argumnent:
>  Used ARRAY_SIZE(combined) [4] instead of sizeof(u32).
>
>  Changes in v5:
>  new, split fixes from changes needed for ACPI support.
>
>  drivers/iio/proximity/sx9310.c | 40 ++++++++++++++++++++++++----------
>  1 file changed, 28 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> index 394c2afe0f233..289c76bb3b024 100644
> --- a/drivers/iio/proximity/sx9310.c
> +++ b/drivers/iio/proximity/sx9310.c
> @@ -1213,17 +1213,17 @@ static int sx9310_init_compensation(struct iio_dev *indio_dev)
>  }
>
>  static const struct sx9310_reg_default *
> -sx9310_get_default_reg(struct sx9310_data *data, int i,
> +sx9310_get_default_reg(struct sx9310_data *data, int idx,
>                        struct sx9310_reg_default *reg_def)
>  {
> -       int ret;
>         const struct device_node *np = data->client->dev.of_node;
> -       u32 combined[SX9310_NUM_CHANNELS] = { 4, 4, 4, 4 };
> +       u32 combined[SX9310_NUM_CHANNELS];
> +       u32 start = 0, raw = 0, pos = 0;
>         unsigned long comb_mask = 0;
> +       int ret, i, count;
>         const char *res;
> -       u32 start = 0, raw = 0, pos = 0;
>
> -       memcpy(reg_def, &sx9310_default_regs[i], sizeof(*reg_def));
> +       memcpy(reg_def, &sx9310_default_regs[idx], sizeof(*reg_def));
>         if (!np)
>                 return reg_def;
>
> @@ -1234,15 +1234,31 @@ sx9310_get_default_reg(struct sx9310_data *data, int i,
>                         reg_def->def |= SX9310_REG_PROX_CTRL2_SHIELDEN_GROUND;
>                 }
>
> -               reg_def->def &= ~SX9310_REG_PROX_CTRL2_COMBMODE_MASK;
> -               of_property_read_u32_array(np, "semtech,combined-sensors",
> -                                          combined, ARRAY_SIZE(combined));
> -               for (i = 0; i < ARRAY_SIZE(combined); i++) {
> -                       if (combined[i] <= SX9310_NUM_CHANNELS)
> -                               comb_mask |= BIT(combined[i]);
> +               count = of_property_count_elems_of_size(np, "semtech,combined-sensors",
> +                                                       sizeof(u32));

instead of doing this manual validation with arrays, why not take the
error codes from of_property_read_u32_array() and check them?

               ret = of_property_read_u32_array(np, "semtech,combined-sensors",
                                           combined, ARRAY_SIZE(combined));

checking for ret < 0 looks sufficient;
it should return an error code if the number of elements in the DT
array isn't exactly ARRAY_SIZE(combined)

but stepping back a bit, the current logic (before this patch) looks
reasonably ok to me;
albeit, it's a bit quirky; and may require some more explanation
somewhere, also in the DT

  semtech,combined-sensors:
    $ref: /schemas/types.yaml#/definitions/uint32-array
    description: |
      List of which sensors are combined and represented by CS3.
      Possible values are -
      3        - CS3 (internal)
      0 1      - CS0 + CS1
      1 2      - CS1 + CS2 (default)
      0 1 2 3  - CS0 + CS1 + CS2 + CS3
    items:
      enum: [ 0, 1, 2, 3 ]
    minItems: 1
    maxItems: 4

i mean, if nothing is defined there, value is 4 for the elements that
are not defined in the DT;

but i think there may be a bug, in the fact that number of elements in
the array must be 4 (no more, no less)
that is, when reading the DT, it implies a variable array size of 1 to
4, which doesn't seem true in the code;

maybe a better idea would be to use of_property_read_***variable***_u32_array()
this would allow for a flexible array size;

               count = of_property_read_variable_u32_array(np,
"semtech,combined-sensors",
                                           combined, 1,
ARRAY_SIZE(combined));   // min 1 , max 4 elements
               // count must be int, so that if it is negative, the
array doesn't loop;
                for (i = 0; i < count; i++) {
                        if (combined[i] <= SX9310_NUM_CHANNELS)
                                comb_mask |= BIT(combined[i]);
                }


> +               if (count > 0 && count <= ARRAY_SIZE(combined)) {
> +                       ret = of_property_read_u32_array(np, "semtech,combined-sensors",
> +                                                        combined, count);
> +                       if (ret)
> +                               break;
> +               } else {
> +                       /*
> +                        * Either the property does not exist in the DT or the
> +                        * number of entries is incorrect.
> +                        */
> +                       break;
> +               }
> +               for (i = 0; i < count; i++) {
> +                       if (combined[i] >= SX9310_NUM_CHANNELS) {
> +                               /* Invalid sensor (invalid DT). */
> +                               break;
> +                       }
> +                       comb_mask |= BIT(combined[i]);
>                 }
> +               if (i < count)
> +                       break;
>
> -               comb_mask &= 0xf;
> +               reg_def->def &= ~SX9310_REG_PROX_CTRL2_COMBMODE_MASK;
>                 if (comb_mask == (BIT(3) | BIT(2) | BIT(1) | BIT(0)))
>                         reg_def->def |= SX9310_REG_PROX_CTRL2_COMBMODE_CS0_CS1_CS2_CS3;
>                 else if (comb_mask == (BIT(1) | BIT(2)))
> --
> 2.31.0.291.g576ba9dcdaf-goog
>
Andy Shevchenko March 22, 2021, 1:28 p.m. UTC | #2
On Mon, Mar 22, 2021 at 1:16 PM Alexandru Ardelean
<ardeleanalex@gmail.com> wrote:
> On Mon, Mar 22, 2021 at 9:33 AM Gwendal Grignou <gwendal@chromium.org> wrote:

...

> but i think there may be a bug, in the fact that number of elements in
> the array must be 4 (no more, no less)
> that is, when reading the DT, it implies a variable array size of 1 to
> 4, which doesn't seem true in the code;
>
> maybe a better idea would be to use of_property_read_***variable***_u32_array()
> this would allow for a flexible array size;

Wouldn't work in conjunction with the second patch.
The above API is OF specific.

>                count = of_property_read_variable_u32_array(np,
> "semtech,combined-sensors",
>                                            combined, 1,
> ARRAY_SIZE(combined));   // min 1 , max 4 elements
>                // count must be int, so that if it is negative, the
> array doesn't loop;
>                 for (i = 0; i < count; i++) {
>                         if (combined[i] <= SX9310_NUM_CHANNELS)
>                                 comb_mask |= BIT(combined[i]);
>                 }
>
Alexandru Ardelean March 22, 2021, 3:16 p.m. UTC | #3
On Mon, Mar 22, 2021 at 3:29 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Mon, Mar 22, 2021 at 1:16 PM Alexandru Ardelean
> <ardeleanalex@gmail.com> wrote:
> > On Mon, Mar 22, 2021 at 9:33 AM Gwendal Grignou <gwendal@chromium.org> wrote:
>
> ...
>
> > but i think there may be a bug, in the fact that number of elements in
> > the array must be 4 (no more, no less)
> > that is, when reading the DT, it implies a variable array size of 1 to
> > 4, which doesn't seem true in the code;
> >
> > maybe a better idea would be to use of_property_read_***variable***_u32_array()
> > this would allow for a flexible array size;
>
> Wouldn't work in conjunction with the second patch.
> The above API is OF specific.

oh
good point

>
> >                count = of_property_read_variable_u32_array(np,
> > "semtech,combined-sensors",
> >                                            combined, 1,
> > ARRAY_SIZE(combined));   // min 1 , max 4 elements
> >                // count must be int, so that if it is negative, the
> > array doesn't loop;
> >                 for (i = 0; i < count; i++) {
> >                         if (combined[i] <= SX9310_NUM_CHANNELS)
> >                                 comb_mask |= BIT(combined[i]);
> >                 }
> >
>
> --
> With Best Regards,
> Andy Shevchenko
diff mbox series

Patch

diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
index 394c2afe0f233..289c76bb3b024 100644
--- a/drivers/iio/proximity/sx9310.c
+++ b/drivers/iio/proximity/sx9310.c
@@ -1213,17 +1213,17 @@  static int sx9310_init_compensation(struct iio_dev *indio_dev)
 }
 
 static const struct sx9310_reg_default *
-sx9310_get_default_reg(struct sx9310_data *data, int i,
+sx9310_get_default_reg(struct sx9310_data *data, int idx,
 		       struct sx9310_reg_default *reg_def)
 {
-	int ret;
 	const struct device_node *np = data->client->dev.of_node;
-	u32 combined[SX9310_NUM_CHANNELS] = { 4, 4, 4, 4 };
+	u32 combined[SX9310_NUM_CHANNELS];
+	u32 start = 0, raw = 0, pos = 0;
 	unsigned long comb_mask = 0;
+	int ret, i, count;
 	const char *res;
-	u32 start = 0, raw = 0, pos = 0;
 
-	memcpy(reg_def, &sx9310_default_regs[i], sizeof(*reg_def));
+	memcpy(reg_def, &sx9310_default_regs[idx], sizeof(*reg_def));
 	if (!np)
 		return reg_def;
 
@@ -1234,15 +1234,31 @@  sx9310_get_default_reg(struct sx9310_data *data, int i,
 			reg_def->def |= SX9310_REG_PROX_CTRL2_SHIELDEN_GROUND;
 		}
 
-		reg_def->def &= ~SX9310_REG_PROX_CTRL2_COMBMODE_MASK;
-		of_property_read_u32_array(np, "semtech,combined-sensors",
-					   combined, ARRAY_SIZE(combined));
-		for (i = 0; i < ARRAY_SIZE(combined); i++) {
-			if (combined[i] <= SX9310_NUM_CHANNELS)
-				comb_mask |= BIT(combined[i]);
+		count = of_property_count_elems_of_size(np, "semtech,combined-sensors",
+							sizeof(u32));
+		if (count > 0 && count <= ARRAY_SIZE(combined)) {
+			ret = of_property_read_u32_array(np, "semtech,combined-sensors",
+							 combined, count);
+			if (ret)
+				break;
+		} else {
+			/*
+			 * Either the property does not exist in the DT or the
+			 * number of entries is incorrect.
+			 */
+			break;
+		}
+		for (i = 0; i < count; i++) {
+			if (combined[i] >= SX9310_NUM_CHANNELS) {
+				/* Invalid sensor (invalid DT). */
+				break;
+			}
+			comb_mask |= BIT(combined[i]);
 		}
+		if (i < count)
+			break;
 
-		comb_mask &= 0xf;
+		reg_def->def &= ~SX9310_REG_PROX_CTRL2_COMBMODE_MASK;
 		if (comb_mask == (BIT(3) | BIT(2) | BIT(1) | BIT(0)))
 			reg_def->def |= SX9310_REG_PROX_CTRL2_COMBMODE_CS0_CS1_CS2_CS3;
 		else if (comb_mask == (BIT(1) | BIT(2)))