2022-01-07 14:44:35

by Jiasheng Jiang

Subject: [PATCH v2] thermal/int340x_thermal: Check for null pointer after calling kmemdup

As the possible failure of the allocation, kmemdup() may return NULL
pointer.
Then the 'bin_attr_data_vault.private' will be NULL pointer but the
'bin_attr_data_vault.size' is not 0.
Therefore, it should be better to check the return value of kmemdup() to
avoid the wrong size.

Fixes: 0ba13c763aac ("thermal/int340x_thermal: Export GDDV")
Signed-off-by: Jiasheng Jiang <[email protected]>
---
Changelog

v1 -> v2

* Change 1. Use out_kfree to simplify the code.
---
.../thermal/intel/int340x_thermal/int3400_thermal.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
index 19926beeb3b7..f869aeb087d3 100644
--- a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
+++ b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
@@ -457,17 +457,21 @@ static void int3400_setup_gddv(struct int3400_thermal_priv *priv)

obj = buffer.pointer;
if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 1
- || obj->package.elements[0].type != ACPI_TYPE_BUFFER) {
- kfree(buffer.pointer);
- return;
- }
+ || obj->package.elements[0].type != ACPI_TYPE_BUFFER)
+ goto out_kfree;

priv->data_vault = kmemdup(obj->package.elements[0].buffer.pointer,
obj->package.elements[0].buffer.length,
GFP_KERNEL);
+ if (!priv->data_vault)
+ goto out_kfree;
+
bin_attr_data_vault.private = priv->data_vault;
bin_attr_data_vault.size = obj->package.elements[0].buffer.length;
kfree(buffer.pointer);
+
+out_kfree:
+ kfree(buffer.pointer);
}

static int int3400_thermal_probe(struct platform_device *pdev)
--
2.25.1

2022-01-26 03:08:02

by Rafael J. Wysocki

Subject: Re: [PATCH v2] thermal/int340x_thermal: Check for null pointer after calling kmemdup

On Fri, Jan 7, 2022 at 3:44 PM Jiasheng Jiang <[email protected]> wrote:
>
> As the possible failure of the allocation, kmemdup() may return NULL
> pointer.
> Then the 'bin_attr_data_vault.private' will be NULL pointer but the
> 'bin_attr_data_vault.size' is not 0.
> Therefore, it should be better to check the return value of kmemdup() to
> avoid the wrong size.
>
> Fixes: 0ba13c763aac ("thermal/int340x_thermal: Export GDDV")
> Signed-off-by: Jiasheng Jiang <[email protected]>
> ---
> Changelog
>
> v1 -> v2
>
> * Change 1. Use out_kfree to simplify the code.
> ---
> .../thermal/intel/int340x_thermal/int3400_thermal.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> index 19926beeb3b7..f869aeb087d3 100644
> --- a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> +++ b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> @@ -457,17 +457,21 @@ static void int3400_setup_gddv(struct int3400_thermal_priv *priv)
>
> obj = buffer.pointer;
> if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count != 1
> - || obj->package.elements[0].type != ACPI_TYPE_BUFFER) {
> - kfree(buffer.pointer);
> - return;
> - }
> + || obj->package.elements[0].type != ACPI_TYPE_BUFFER)
> + goto out_kfree;

This change isn't strictly necessary.

>
> priv->data_vault = kmemdup(obj->package.elements[0].buffer.pointer,
> obj->package.elements[0].buffer.length,
> GFP_KERNEL);
> + if (!priv->data_vault)
> + goto out_kfree;
> +
> bin_attr_data_vault.private = priv->data_vault;
> bin_attr_data_vault.size = obj->package.elements[0].buffer.length;
> kfree(buffer.pointer);
> +
> +out_kfree:
> + kfree(buffer.pointer);

On success, this would be the second kfree() for the same pointer in a
row, which would be a bug.

> }
>
> static int int3400_thermal_probe(struct platform_device *pdev)
> --