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hwmon: (corsair-cpro) Protect ccp->wait_input_report with a spinlock

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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: 40c3a44542 ("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>
This commit is contained in:
Aleksa Savic 2024-05-04 11:25:03 +02:00 committed by Guenter Roeck
parent 3a034a7b07
commit d02abd57e7
1 changed files with 19 additions and 5 deletions
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24
drivers/hwmon/corsair-cpro.c
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@ -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);