diff options
| author | Martijn Coenen <maco@android.com> | 2018-02-16 09:47:15 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-10-07 18:53:19 +0200 |
| commit | b6c6212514fe9f2387fc6677181028d4a9ae20c7 (patch) | |
| tree | 9e3fede69bd868901269813d8939d737387807dd /drivers/android | |
| parent | a494a71146a1cf3f48bb94cf33981db1f027e6a0 (diff) | |
ANDROID: binder: synchronize_rcu() when using POLLFREE.
commit 5eeb2ca02a2f6084fc57ae5c244a38baab07033a upstream.
To prevent races with ep_remove_waitqueue() removing the
waitqueue at the same time.
Reported-by: syzbot+a2a3c4909716e271487e@syzkaller.appspotmail.com
Signed-off-by: Martijn Coenen <maco@android.com>
Cc: stable <stable@vger.kernel.org> # 4.14+
Signed-off-by: Mattias Nissler <mnissler@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/android')
| -rw-r--r-- | drivers/android/binder.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/android/binder.c b/drivers/android/binder.c index b6f4baab6848..e12288c245b5 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2641,6 +2641,15 @@ static int binder_free_thread(struct binder_proc *proc, wake_up_poll(&thread->wait, POLLHUP | POLLFREE); } + /* + * This is needed to avoid races between wake_up_poll() above and + * and ep_remove_waitqueue() called for other reasons (eg the epoll file + * descriptor being closed); ep_remove_waitqueue() holds an RCU read + * lock, so we can be sure it's done after calling synchronize_rcu(). + */ + if (thread->looper & BINDER_LOOPER_STATE_POLL) + synchronize_rcu(); + if (send_reply) binder_send_failed_reply(send_reply, BR_DEAD_REPLY); binder_release_work(&thread->todo); |