linux-kernel - [PATCH 1/3] hwmon: (corsair-cpro) Use a separate buffer for sending commands

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Date: Sat,  4 May 2024 11:25:01 +0200
From: Aleksa Savic <savicaleksa83@...il.com>
To: linux-hwmon@...r.kernel.org
Cc: Jonas Malaco <jonas@...tocubo.io>,
	Aleksa Savic <savicaleksa83@...il.com>,
	Marius Zachmann <mail@...iuszachmann.de>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] hwmon: (corsair-cpro) Use a separate buffer for sending commands

Introduce cmd_buffer, a separate buffer for storing only
the command that is sent to the device. Before this separation,
the existing buffer was shared for both the command and the
report received in ccp_raw_event(), which was copied into it.

However, because of hidraw, the raw event parsing may be triggered
in the middle of sending a command, resulting in outputting gibberish
to the device. Using a separate buffer resolves this.

Fixes: 40c3a4454225 ("hwmon: add Corsair Commander Pro driver")
Signed-off-by: Aleksa Savic <savicaleksa83@...il.com>
---
 drivers/hwmon/corsair-cpro.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/hwmon/corsair-cpro.c b/drivers/hwmon/corsair-cpro.c
index a284a02839fb..8d85f66f8143 100644
--- a/drivers/hwmon/corsair-cpro.c
+++ b/drivers/hwmon/corsair-cpro.c
@@ -79,6 +79,7 @@ struct ccp_device {
 	struct device *hwmon_dev;
 	struct completion wait_input_report;
 	struct mutex mutex; /* whenever buffer is used, lock before send_usb_cmd */
+	u8 *cmd_buffer;
 	u8 *buffer;
 	int target[6];
 	DECLARE_BITMAP(temp_cnct, NUM_TEMP_SENSORS);
@@ -111,15 +112,15 @@ static int send_usb_cmd(struct ccp_device *ccp, u8 command, u8 byte1, u8 byte2,
 	unsigned long t;
 	int ret;
 
-	memset(ccp->buffer, 0x00, OUT_BUFFER_SIZE);
-	ccp->buffer[0] = command;
-	ccp->buffer[1] = byte1;
-	ccp->buffer[2] = byte2;
-	ccp->buffer[3] = byte3;
+	memset(ccp->cmd_buffer, 0x00, OUT_BUFFER_SIZE);
+	ccp->cmd_buffer[0] = command;
+	ccp->cmd_buffer[1] = byte1;
+	ccp->cmd_buffer[2] = byte2;
+	ccp->cmd_buffer[3] = byte3;
 
 	reinit_completion(&ccp->wait_input_report);
 
-	ret = hid_hw_output_report(ccp->hdev, ccp->buffer, OUT_BUFFER_SIZE);
+	ret = hid_hw_output_report(ccp->hdev, ccp->cmd_buffer, OUT_BUFFER_SIZE);
 	if (ret < 0)
 		return ret;
 
@@ -492,7 +493,11 @@ static int ccp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	if (!ccp)
 		return -ENOMEM;
 
-	ccp->buffer = devm_kmalloc(&hdev->dev, OUT_BUFFER_SIZE, GFP_KERNEL);
+	ccp->cmd_buffer = devm_kmalloc(&hdev->dev, OUT_BUFFER_SIZE, GFP_KERNEL);
+	if (!ccp->cmd_buffer)
+		return -ENOMEM;
+
+	ccp->buffer = devm_kmalloc(&hdev->dev, IN_BUFFER_SIZE, GFP_KERNEL);
 	if (!ccp->buffer)
 		return -ENOMEM;
 
-- 
2.44.0