HID: usbhid: Fix race between usbhid_close() and usbhid_stop()
commit 0ed08faded1da03eb3def61502b27f81aef2e615 upstream.
The syzbot fuzzer discovered a bad race between in the usbhid driver
between usbhid_stop() and usbhid_close(). In particular,
usbhid_stop() does:
usb_free_urb(usbhid->urbin);
...
usbhid->urbin = NULL; /* don't mess up next start */
and usbhid_close() does:
usb_kill_urb(usbhid->urbin);
with no mutual exclusion. If the two routines happen to run
concurrently so that usb_kill_urb() is called in between the
usb_free_urb() and the NULL assignment, it will access the
deallocated urb structure -- a use-after-free bug.
This patch adds a mutex to the usbhid private structure and uses it to
enforce mutual exclusion of the usbhid_start(), usbhid_stop(),
usbhid_open() and usbhid_close() callbacks.
Reported-and-tested-by: syzbot+7bf5a7b0f0a1f9446f4c@syzkaller.appspotmail.com
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@vger.kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed
