On Thu, Sep 02, 2021 at 08:35:35AM -0700, Todd Kjos wrote: > On Tue, Aug 31, 2021 at 12:24 AM Martijn Coenen <maco@xxxxxxxxxxx> wrote: > > > > On Mon, Aug 30, 2021 at 9:51 PM 'Todd Kjos' via kernel-team > > <kernel-team@xxxxxxxxxxx> wrote: > > > > > > During BC_FREE_BUFFER processing, the BINDER_TYPE_FDA object > > > cleanup may close 1 or more fds. The close operations are > > > completed using the task work mechanism -- which means the thread > > > needs to return to userspace or the file object may never be > > > dereferenced -- which can lead to hung processes. > > > > > > Force the binder thread back to userspace if an fd is closed during > > > BC_FREE_BUFFER handling. > > > > > > Signed-off-by: Todd Kjos <tkjos@xxxxxxxxxx> > > Reviewed-by: Martijn Coenen <maco@xxxxxxxxxxx> > > Please also add to stable releases 5.4 and later. It would be better if this had a fixes tag so we knew which is the first buggy commit. There was a long Project Zero article about the Bad Binder exploit because commit f5cb779ba163 ("ANDROID: binder: remove waitqueue when thread exits.") was marked as # 4.14 but it didn't have a Fixes tag and the actual buggy commit was in 4.9. regards, dan carpenter