On 2019-01-19, Mattias Jacobsson wrote:
> In preparation for adding WMI support to MODULE_DEVICE_TABLE() move the
> definition of struct wmi_device_id to mod_devicetable.h and inline
> guid_string in the struct.
>
> Changing guid_string to an inline char array changes the loop conditions
> when looping over an array of struct wmi_device_id. Therefore update
> wmi_dev_match()'s loop to check for an empty guid_string instead of a
> NULL pointer.
>
> Signed-off-by: Mattias Jacobsson <2pi@xxxxxx>
> ---
> drivers/platform/x86/wmi.c | 2 +-
> include/linux/mod_devicetable.h | 13 +++++++++++++
> include/linux/wmi.h | 5 +----
> 3 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
> index bea35be68706..d7a2f5c8b959 100644
> --- a/drivers/platform/x86/wmi.c
> +++ b/drivers/platform/x86/wmi.c
> @@ -768,7 +768,7 @@ static int wmi_dev_match(struct device *dev, struct device_driver *driver)
> struct wmi_block *wblock = dev_to_wblock(dev);
> const struct wmi_device_id *id = wmi_driver->id_table;
>
> - while (id->guid_string) {
> + while (id->guid_string[0] != '\0') {
While looking through my patchset again I realized that I've inherited a potential
null pointer dereference situation. This is relevant regardless of this patchset
and I've therefore submitted a separate patch for that [1]. Further versions of
this patchset will explicitly depend on [1], as this doesn't require any actual
changes to this patchset, I'll wait for more comments before sending it.
[1]: https://lkml.kernel.org/r/20190122200302.19861-1-2pi@xxxxxx
> uuid_le driver_guid;
>
> if (WARN_ON(uuid_le_to_bin(id->guid_string, &driver_guid)))
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index f9bd2f34b99f..ccc9bd4f32d2 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -779,4 +779,17 @@ struct typec_device_id {
> kernel_ulong_t driver_data;
> };
>
> +/* WMI */
> +
> +#define WMI_MODULE_PREFIX "wmi:"
> +#define WMI_GUID_STRING_LEN 36
> +
> +/**
> + * struct wmi_device_id - WMI device identifier
> + * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
> + */
> +struct wmi_device_id {
> + const char guid_string[WMI_GUID_STRING_LEN+1];
> +};
> +
> #endif /* LINUX_MOD_DEVICETABLE_H */
> diff --git a/include/linux/wmi.h b/include/linux/wmi.h
> index 4757cb5077e5..592f81afecbb 100644
> --- a/include/linux/wmi.h
> +++ b/include/linux/wmi.h
> @@ -18,6 +18,7 @@
>
> #include <linux/device.h>
> #include <linux/acpi.h>
> +#include <linux/mod_devicetable.h>
> #include <uapi/linux/wmi.h>
>
> struct wmi_device {
> @@ -39,10 +40,6 @@ extern union acpi_object *wmidev_block_query(struct wmi_device *wdev,
>
> extern int set_required_buffer_size(struct wmi_device *wdev, u64 length);
>
> -struct wmi_device_id {
> - const char *guid_string;
> -};
> -
> struct wmi_driver {
> struct device_driver driver;
> const struct wmi_device_id *id_table;
> --
> 2.20.1
>
Thanks,
Mattias
