[PATCH v2 09/12] HID: hid-tmff: clean up usage of 'driver_data'

[Pawel Zalewski (The Capable Hub)]

This module is using the 'hid_device_id::driver_data' field
as a valid pointer to dereference. The hid subsystem supports
injecting a 'new_id' device from the command line and so it is
more convenient to have this value to be an integer - that way
userspace can select a valid pointer within the driver via an
index.

Lets make this possible by storing an index to the table of
pointers 'ff_bits_table' there as opposed to the pointer address
directly.

The retrieval is bounded at runtime by the 'ff_bits_table_index'
enum to avoid dereferencing OOB objects.

Signed-off-by: Pawel Zalewski (The Capable Hub) <pzalewski@xxxxxxxxxxxxxxxxxxxx>
---
 drivers/hid/hid-tmff.c | 48 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 11 deletions(-)

diff --git a/drivers/hid/hid-tmff.c b/drivers/hid/hid-tmff.c
index 423f395d01ac..93de756dd30e 100644
--- a/drivers/hid/hid-tmff.c
+++ b/drivers/hid/hid-tmff.c
@@ -34,6 +34,17 @@ static const signed short ff_joystick[] = {
 	-1
 };
 
+enum ff_bits_table_index {
+	FF_BITS_TABLE_RUMBLE,
+	FF_BITS_TABLE_JOYSTICK,
+	NUM_OF_FF_BITS_IN_TABLE
+};
+
+static const signed short *ff_bits_table[] = {
+	[FF_BITS_TABLE_RUMBLE]		= ff_rumble,
+	[FF_BITS_TABLE_JOYSTICK]	= ff_joystick
+};
+
 #ifdef CONFIG_THRUSTMASTER_FF
 
 /* Usages for thrustmaster devices I know about */
@@ -210,9 +221,18 @@ static inline int tmff_init(struct hid_device *hid, const signed short *ff_bits)
 }
 #endif
 
+static const signed short *get_ff_bits(enum ff_bits_table_index index)
+{
+	if (index >= NUM_OF_FF_BITS_IN_TABLE)
+		return NULL;
+
+	return ff_bits_table[index];
+}
+
 static int tm_probe(struct hid_device *hdev, const struct hid_device_id *id)
 {
 	int ret;
+	const signed short *ff_bits = get_ff_bits(id->driver_data);
 
 	ret = hid_parse(hdev);
 	if (ret) {
@@ -226,7 +246,13 @@ static int tm_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		goto err;
 	}
 
-	tmff_init(hdev, (void *)id->driver_data);
+	if (!ff_bits) {
+		hid_err(hdev, "no ff_bits found\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	tmff_init(hdev, ff_bits);
 
 	return 0;
 err:
@@ -235,25 +261,25 @@ static int tm_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
 static const struct hid_device_id tm_devices[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb300),
-		.driver_data = (unsigned long)ff_rumble },
+		.driver_data = FF_BITS_TABLE_RUMBLE },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb304),   /* FireStorm Dual Power 2 (and 3) */
-		.driver_data = (unsigned long)ff_rumble },
+		.driver_data = FF_BITS_TABLE_RUMBLE },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, THRUSTMASTER_DEVICE_ID_2_IN_1_DT),   /* Dual Trigger 2-in-1 */
-		.driver_data = (unsigned long)ff_rumble },
+		.driver_data = FF_BITS_TABLE_RUMBLE },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb323),   /* Dual Trigger 3-in-1 (PC Mode) */
-		.driver_data = (unsigned long)ff_rumble },
+		.driver_data = FF_BITS_TABLE_RUMBLE },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb324),   /* Dual Trigger 3-in-1 (PS3 Mode) */
-		.driver_data = (unsigned long)ff_rumble },
+		.driver_data = FF_BITS_TABLE_RUMBLE },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb605),   /* NASCAR PRO FF2 Wheel */
-		.driver_data = (unsigned long)ff_joystick },
+		.driver_data = FF_BITS_TABLE_JOYSTICK },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb651),	/* FGT Rumble Force Wheel */
-		.driver_data = (unsigned long)ff_rumble },
+		.driver_data = FF_BITS_TABLE_RUMBLE },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb653),	/* RGT Force Feedback CLUTCH Raging Wheel */
-		.driver_data = (unsigned long)ff_joystick },
+		.driver_data = FF_BITS_TABLE_JOYSTICK },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb654),	/* FGT Force Feedback Wheel */
-		.driver_data = (unsigned long)ff_joystick },
+		.driver_data = FF_BITS_TABLE_JOYSTICK },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_THRUSTMASTER, 0xb65a),	/* F430 Force Feedback Wheel */
-		.driver_data = (unsigned long)ff_joystick },
+		.driver_data = FF_BITS_TABLE_JOYSTICK },
 	{ }
 };
 MODULE_DEVICE_TABLE(hid, tm_devices);

-- 
2.43.0