From f0f25649c86f2962e8e4497b699fe6b151a18b1a Mon Sep 17 00:00:00 2001 From: "dan.carpenter@oracle.com" Date: Wed, 15 Jan 2020 20:46:28 +0300 Subject: HID: hiddev: Fix race in in hiddev_disconnect() commit 5c02c447eaeda29d3da121a2e17b97ccaf579b51 upstream. Syzbot reports that "hiddev" is used after it's free in hiddev_disconnect(). The hiddev_disconnect() function sets "hiddev->exist = 0;" so hiddev_release() can free it as soon as we drop the "existancelock" lock. This patch moves the mutex_unlock(&hiddev->existancelock) until after we have finished using it. Reported-by: syzbot+784ccb935f9900cc7c9e@syzkaller.appspotmail.com Fixes: 7f77897ef2b6 ("HID: hiddev: fix potential use-after-free") Suggested-by: Alan Stern Signed-off-by: Dan Carpenter Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- drivers/hid/usbhid/hiddev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/hid') diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c index 8903ea09ac58..dbdd265075da 100644 --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -962,9 +962,9 @@ void hiddev_disconnect(struct hid_device *hid) hiddev->exist = 0; if (hiddev->open) { - mutex_unlock(&hiddev->existancelock); usbhid_close(hiddev->hid); wake_up_interruptible(&hiddev->wait); + mutex_unlock(&hiddev->existancelock); } else { mutex_unlock(&hiddev->existancelock); kfree(hiddev); -- cgit v1.2.3