[PATCH] usb: gadget: f_hid: do not copy_from_user() under a spinlock

[Linkai Gong]

f_hidg_get_report() already copied the report from userspace into a
new entry, then called copy_from_user() again under
get_report_spinlock. That can fault and sleep in atomic context.

Update the existing entry with memcpy() from the copy already taken.

Fixes: a139c98f760e ("USB: gadget: f_hid: Add GET_REPORT via userspace IOCTL")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Linkai Gong <gonglinkai@xxxxxxxxxx>
---
 drivers/usb/gadget/function/f_hid.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index 3c6b43d06a6d..e4621e5a0b69 100644
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -667,14 +667,9 @@ static int f_hidg_get_report(struct file *file, struct usb_hidg_report __user *b
 	ptr = f_hidg_search_for_report(hidg, report_id);
 
 	if (ptr) {
-		/* Report already exists in list - update it */
-		if (copy_from_user(&ptr->report_data, buffer,
-				sizeof(struct usb_hidg_report))) {
-			spin_unlock_irqrestore(&hidg->get_report_spinlock, flags);
-			ERROR(cdev, "copy_from_user error\n");
-			kfree(entry);
-			return -EINVAL;
-		}
+		/* Report already exists; data was copied before taking the lock. */
+		memcpy(&ptr->report_data, &entry->report_data,
+		       sizeof(struct usb_hidg_report));
 		kfree(entry);
 	} else {
 		/* Report does not exist in list - add it */
-- 
2.25.1