diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 940d163788a8..4a18847983f7 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -633,7 +633,7 @@ static ssize_t dwc3_store_ep_num(struct file *file, const char __user *ubuf,
 	unsigned int		num, dir, temp;
 	unsigned long		flags;
 
-	if (copy_from_user(kbuf, ubuf, count > 10 ? 10 : count))
+	if (copy_from_user(kbuf, ubuf, min_t(size_t, sizeof(kbuf) - 1, count)))
 		return -EFAULT;
 
 	if (sscanf(kbuf, "%u %u", &num, &dir) != 2)