[PATCH] Input: ati_remote2 - fix type confusion in device attribute handlers

[Haotian Zhang <vulab@iscas.ac.cn>]

The channel_mask and mode_mask attributes are instantiated by the driver
core through struct usb_driver::dev_groups, so they are attached to the
usb_interface bound to the driver, not to the usb_device.  The four
show/store handlers still call to_usb_device(dev), which applies the
struct usb_device container_of() to a struct usb_interface::dev and thus
produces a bogus usb_device pointer.  usb_ifnum_to_if() reads that
pointer as udev->actconfig and dereferences it, and its result is passed
to usb_get_intfdata() without any NULL check, so reading or writing the
world-readable attributes can crash the kernel.

Use to_usb_interface(dev) so the handlers recover the interface that the
attributes belong to, matching the other drivers converted to dev_groups.

Fixes: b20d6bf8014b ("Input: ati-remote2 - use driver core to instantiate device attributes")
Assisted-by: DeepSeek-V4.1-Flash
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
---
 drivers/input/misc/ati_remote2.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/input/misc/ati_remote2.c b/drivers/input/misc/ati_remote2.c
index 8db2dca84975..3e0f874e9b16 100644
--- a/drivers/input/misc/ati_remote2.c
+++ b/drivers/input/misc/ati_remote2.c
@@ -672,8 +672,7 @@ static ssize_t ati_remote2_show_channel_mask(struct device *dev,
 					     struct device_attribute *attr,
 					     char *buf)
 {
-	struct usb_device *udev = to_usb_device(dev);
-	struct usb_interface *intf = usb_ifnum_to_if(udev, 0);
+	struct usb_interface *intf = to_usb_interface(dev);
 	struct ati_remote2 *ar2 = usb_get_intfdata(intf);
 
 	return sprintf(buf, "0x%04x\n", ar2->channel_mask);
@@ -683,8 +682,7 @@ static ssize_t ati_remote2_store_channel_mask(struct device *dev,
 					      struct device_attribute *attr,
 					      const char *buf, size_t count)
 {
-	struct usb_device *udev = to_usb_device(dev);
-	struct usb_interface *intf = usb_ifnum_to_if(udev, 0);
+	struct usb_interface *intf = to_usb_interface(dev);
 	struct ati_remote2 *ar2 = usb_get_intfdata(intf);
 	unsigned int mask;
 	int r;
@@ -720,8 +718,7 @@ static ssize_t ati_remote2_show_mode_mask(struct device *dev,
 					  struct device_attribute *attr,
 					  char *buf)
 {
-	struct usb_device *udev = to_usb_device(dev);
-	struct usb_interface *intf = usb_ifnum_to_if(udev, 0);
+	struct usb_interface *intf = to_usb_interface(dev);
 	struct ati_remote2 *ar2 = usb_get_intfdata(intf);
 
 	return sprintf(buf, "0x%02x\n", ar2->mode_mask);
@@ -731,8 +728,7 @@ static ssize_t ati_remote2_store_mode_mask(struct device *dev,
 					   struct device_attribute *attr,
 					   const char *buf, size_t count)
 {
-	struct usb_device *udev = to_usb_device(dev);
-	struct usb_interface *intf = usb_ifnum_to_if(udev, 0);
+	struct usb_interface *intf = to_usb_interface(dev);
 	struct ati_remote2 *ar2 = usb_get_intfdata(intf);
 	unsigned int mask;
 	int err;
-- 
2.25.1