[PATCH 6.8 209/336] hwmon: (corsair-cpro) Protect ccp->wait_input_report with a spinlock

Greg Kroah-Hartman
2024-05-14T10:47:30Z

From: Aleksa Savic <savicaleksa83@gmail.com>

[ Upstream commit d02abd57e79469a026213f7f5827a98d909f236a ]

Through hidraw, userspace can cause a status report to be sent
from the device. The parsing in ccp_raw_event() may happen in
parallel to a send_usb_cmd() call (which resets the completion
for tracking the report) if it's running on a different CPU where
bottom half interrupts are not disabled.

Add a spinlock around the complete_all() in ccp_raw_event() and
reinit_completion() in send_usb_cmd() to prevent race issues.

Fixes: 40c3a4454225 ("hwmon: add Corsair Commander Pro driver")
Signed-off-by: Aleksa Savic <savicaleksa83@gmail.com>
Acked-by: Marius Zachmann <mail@mariuszachmann.de>
Link: https://lore.kernel.org/r/20240504092504.24158-4-savicaleksa83@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/corsair-cpro.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/corsair-cpro.c b/drivers/hwmon/corsair-cpro.c
index 6ab4d2478b1fd..3e63666a61bd6 100644
--- a/drivers/hwmon/corsair-cpro.c
+++ b/drivers/hwmon/corsair-cpro.c
@@ -16,6 +16,7 @@
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
+#include <linux/spinlock.h>
#include <linux/types.h>

#define USB_VENDOR_ID_CORSAIR 0x1b1c
@@ -77,6 +78,8 @@
struct ccp_device {
struct hid_device *hdev;
struct device *hwmon_dev;
+ /* For reinitializing the completion below */
+ spinlock_t wait_input_report_lock;
struct completion wait_input_report;
struct mutex mutex; /* whenever buffer is used, lock before send_usb_cmd */
u8 *cmd_buffer;
@@ -118,7 +121,15 @@ static int send_usb_cmd(struct ccp_device *ccp, u8 command, u8 byte1, u8 byte2,
ccp->cmd_buffer[2] = byte2;
ccp->cmd_buffer[3] = byte3;

+ /*
+ * Disable raw event parsing for a moment to safely reinitialize the
+ * completion. Reinit is done because hidraw could have triggered
+ * the raw event parsing and marked the ccp->wait_input_report
+ * completion as done.
+ */
+ spin_lock_bh(&ccp->wait_input_report_lock);
reinit_completion(&ccp->wait_input_report);
+ spin_unlock_bh(&ccp->wait_input_report_lock);

ret = hid_hw_output_report(ccp->hdev, ccp->cmd_buffer, OUT_BUFFER_SIZE);
if (ret < 0)
@@ -136,11 +147,12 @@ static int ccp_raw_event(struct hid_device *hdev, struct hid_report *report, u8
struct ccp_device *ccp = hid_get_drvdata(hdev);

/* only copy buffer when requested */
- if (completion_done(&ccp->wait_input_report))
- return 0;
-
- memcpy(ccp->buffer, data, min(IN_BUFFER_SIZE, size));
- complete_all(&ccp->wait_input_report);
+ spin_lock(&ccp->wait_input_report_lock);
+ if (!completion_done(&ccp->wait_input_report)) {
+ memcpy(ccp->buffer, data, min(IN_BUFFER_SIZE, size));
+ complete_all(&ccp->wait_input_report);
+ }
+ spin_unlock(&ccp->wait_input_report_lock);

return 0;
}
@@ -515,7 +527,9 @@ static int ccp_probe(struct hid_device *hdev, const struct hid_device_id *id)

ccp->hdev = hdev;
hid_set_drvdata(hdev, ccp);
+
mutex_init(&ccp->mutex);
+ spin_lock_init(&ccp->wait_input_report_lock);
init_completion(&ccp->wait_input_report);

hid_device_io_start(hdev);
--
2.43.0