| Message ID | 20200115174628.zxpxbpa6bwspjajg@kili.mountain (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 5c02c447eaeda29d3da121a2e17b97ccaf579b51 |
| Delegated to: | Jiri Kosina |
| Headers | show |
| Series | HID: hiddev: Fix race in in hiddev_disconnect() | expand |
On Wed, 15 Jan 2020, Dan Carpenter wrote: > 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 <stern@rowland.harvard.edu> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Applied to for-5.6/upstream-fixes. Thanks,
diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c index a970b809d778..4140dea693e9 100644 --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -932,9 +932,9 @@ void hiddev_disconnect(struct hid_device *hid) hiddev->exist = 0; if (hiddev->open) { - mutex_unlock(&hiddev->existancelock); hid_hw_close(hiddev->hid); wake_up_interruptible(&hiddev->wait); + mutex_unlock(&hiddev->existancelock); } else { mutex_unlock(&hiddev->existancelock); kfree(hiddev);
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 <stern@rowland.harvard.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> --- drivers/hid/usbhid/hiddev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)