From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH 1/1] r8152: fix NULL pointer dereference in r8152_poll Date: Mon, 13 Mar 2017 08:44:09 -0700 Message-ID: <1489419849.28631.85.camel@edumazet-glaptop3.roam.corp.google.com> References: <20170313124727.4681-1-petr.vorel@gmail.com> <1489411084.28631.78.camel@edumazet-glaptop3.roam.corp.google.com> <1489411184.28631.80.camel@edumazet-glaptop3.roam.corp.google.com> <20170313153745.wu7cf254obh2x2gn@dell5510> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, hayeswang@realtek.com, davem@davemloft.net To: Petr Vorel Return-path: Received: from mail-pf0-f196.google.com ([209.85.192.196]:35685 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751266AbdCMPoM (ORCPT ); Mon, 13 Mar 2017 11:44:12 -0400 Received: by mail-pf0-f196.google.com with SMTP id 67so19386745pfg.2 for ; Mon, 13 Mar 2017 08:44:11 -0700 (PDT) In-Reply-To: <20170313153745.wu7cf254obh2x2gn@dell5510> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2017-03-13 at 16:37 +0100, Petr Vorel wrote: > Hi Eric, > > > > The proper work around is to enclose the napi_schedule() in a > > > local_bh_enable()/local_bh_disable() pair. > > > Something like : > > --- a/drivers/net/usb/r8152.c > > +++ b/drivers/net/usb/r8152.c > > @@ -3703,8 +3703,10 @@ static int rtl8152_resume(struct usb_interface *intf) > > napi_enable(&tp->napi); > > clear_bit(SELECTIVE_SUSPEND, &tp->flags); > > smp_mb__after_atomic(); > > + local_bh_disable(); > > if (!list_empty(&tp->rx_done)) > > napi_schedule(&tp->napi); > > + local_bh_enable(); > > Unfortunately this doesn't work. Code in r8152.c doesn't use > local_bh_enable()/local_bh_disable(). I tried to lock it with > spin_lock_bh()/spin_unlock_bh() and with mutex_lock()/mutex_unlock() > but neither work. The local_bh_disable() / local_bh_enable() definitely is the right answer to the issue you described. It does not matter what code in r8152.c currently does. https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=8cf699ec849f4ca1413cea01289bd7d37dbcc626