linux-kernel - [PATCH 1/2] HID: corsair: fix DMA buffers on stack

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Message-Id: <20170112171743.5972-2-johan@kernel.org>
Date:   Thu, 12 Jan 2017 18:17:42 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Jiri Kosina <jikos@...nel.org>
Cc:     Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-input@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        stable <stable@...r.kernel.org>
Subject: [PATCH 1/2] HID: corsair: fix DMA buffers on stack

Not all platforms support DMA to the stack, and specifically since v4.9
this is no longer supported on x86 with VMAP_STACK either.

Note that the macro-mode buffer was larger than necessary.

Fixes: 6f78193ee9ea ("HID: corsair: Add Corsair Vengeance K90 driver")
Cc: stable <stable@...r.kernel.org>
Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/hid/hid-corsair.c | 54 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 42 insertions(+), 12 deletions(-)

diff --git a/drivers/hid/hid-corsair.c b/drivers/hid/hid-corsair.c
index 717704e9ae07..5971907a23b1 100644
--- a/drivers/hid/hid-corsair.c
+++ b/drivers/hid/hid-corsair.c
@@ -148,7 +148,11 @@ static enum led_brightness k90_backlight_get(struct led_classdev *led_cdev)
 	struct usb_interface *usbif = to_usb_interface(dev->parent);
 	struct usb_device *usbdev = interface_to_usbdev(usbif);
 	int brightness;
-	char data[8];
+	char *data;
+
+	data = kmalloc(8, GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
 
 	ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
 			      K90_REQUEST_STATUS,
@@ -158,16 +162,22 @@ static enum led_brightness k90_backlight_get(struct led_classdev *led_cdev)
 	if (ret < 0) {
 		dev_warn(dev, "Failed to get K90 initial state (error %d).\n",
 			 ret);
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
 	brightness = data[4];
 	if (brightness < 0 || brightness > 3) {
 		dev_warn(dev,
 			 "Read invalid backlight brightness: %02hhx.\n",
 			 data[4]);
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
-	return brightness;
+	ret = brightness;
+out:
+	kfree(data);
+
+	return ret;
 }
 
 static enum led_brightness k90_record_led_get(struct led_classdev *led_cdev)
@@ -253,7 +263,11 @@ static ssize_t k90_show_macro_mode(struct device *dev,
 	struct usb_interface *usbif = to_usb_interface(dev->parent);
 	struct usb_device *usbdev = interface_to_usbdev(usbif);
 	const char *macro_mode;
-	char data[8];
+	char *data;
+
+	data = kmalloc(2, GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
 
 	ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
 			      K90_REQUEST_GET_MODE,
@@ -263,7 +277,8 @@ static ssize_t k90_show_macro_mode(struct device *dev,
 	if (ret < 0) {
 		dev_warn(dev, "Failed to get K90 initial mode (error %d).\n",
 			 ret);
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
 
 	switch (data[0]) {
@@ -277,10 +292,15 @@ static ssize_t k90_show_macro_mode(struct device *dev,
 	default:
 		dev_warn(dev, "K90 in unknown mode: %02hhx.\n",
 			 data[0]);
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
 
-	return snprintf(buf, PAGE_SIZE, "%s\n", macro_mode);
+	ret = snprintf(buf, PAGE_SIZE, "%s\n", macro_mode);
+out:
+	kfree(data);
+
+	return ret;
 }
 
 static ssize_t k90_store_macro_mode(struct device *dev,
@@ -320,7 +340,11 @@ static ssize_t k90_show_current_profile(struct device *dev,
 	struct usb_interface *usbif = to_usb_interface(dev->parent);
 	struct usb_device *usbdev = interface_to_usbdev(usbif);
 	int current_profile;
-	char data[8];
+	char *data;
+
+	data = kmalloc(8, GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
 
 	ret = usb_control_msg(usbdev, usb_rcvctrlpipe(usbdev, 0),
 			      K90_REQUEST_STATUS,
@@ -330,16 +354,22 @@ static ssize_t k90_show_current_profile(struct device *dev,
 	if (ret < 0) {
 		dev_warn(dev, "Failed to get K90 initial state (error %d).\n",
 			 ret);
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
 	current_profile = data[7];
 	if (current_profile < 1 || current_profile > 3) {
 		dev_warn(dev, "Read invalid current profile: %02hhx.\n",
 			 data[7]);
-		return -EIO;
+		ret = -EIO;
+		goto out;
 	}
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", current_profile);
+	ret = snprintf(buf, PAGE_SIZE, "%d\n", current_profile);
+out:
+	kfree(data);
+
+	return ret;
 }
 
 static ssize_t k90_store_current_profile(struct device *dev,
-- 
2.10.2