From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752019AbcADPZP (ORCPT ); Mon, 4 Jan 2016 10:25:15 -0500 Received: from mail-pf0-f179.google.com ([209.85.192.179]:33645 "EHLO mail-pf0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751308AbcADPZM (ORCPT ); Mon, 4 Jan 2016 10:25:12 -0500 Message-ID: <1451921108.8255.74.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: [PATCH] net: Fix potential NULL pointer dereference in __skb_try_recv_datagram From: Eric Dumazet To: Jacob Siverskog Cc: Cong Wang , Eric Dumazet , David Miller , Rainer Weikusat , netdev , Herbert Xu , Konstantin Khlebnikov , Al Viro , LKML Date: Mon, 04 Jan 2016 10:25:08 -0500 In-Reply-To: References: <1451416224-15871-1-git-send-email-jacob@teenage.engineering> <87y4cdyrbn.fsf@doppelsaurus.mobileactivedefense.com> <20151229.150843.2021692616139434395.davem@davemloft.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2016-01-04 at 10:10 +0100, Jacob Siverskog wrote: > On Wed, Dec 30, 2015 at 11:30 PM, Cong Wang wrote: > > On Wed, Dec 30, 2015 at 6:30 AM, Jacob Siverskog > > wrote: > >> On Wed, Dec 30, 2015 at 2:26 PM, Eric Dumazet wrote: > >>> How often can you trigger this bug ? > >> > >> Ok. I don't have a good repro to trigger it unfortunately, I've seen it just a > >> few times when bringing up/down network interfaces. Does the trace > >> give any clue? > >> > > > > A little bit. You need to help people to narrow down the problem > > because there are too many places using skb->next and skb->prev. > > > > Since you mentioned it seems related to network interface flip, > > what network interfaces are you using? What's is your TC setup? > > > > Thanks. > > The system contains only one physical network interface (TI WL1837, > wl18xx module). > The state prior to the crash was as follows: > - One virtual network interface active (as STA, associated with access point) > - Bluetooth (BLE only) active (same physical chip, co-existence, > btwilink/st_drv modules) > > Actions made around the time of the crash: > - Bluetooth disabled > - One additional virtual network interface brought up (also as STA) > > I believe the crash occurred between these two actions. I just saw > that there are some interesting events in the log prior to the crash: > kernel: Bluetooth: Unable to push skb to HCI core(-6) > kernel: (stc): proto stack 4's ->recv failed > kernel: (stc): remove_channel_from_table: id 3 > kernel: (stc): remove_channel_from_table: id 2 > kernel: (stc): remove_channel_from_table: id 4 > kernel: (stc): all chnl_ids unregistered > kernel: (stk) :ldisc_install = 0(stc): st_tty_close > > The first print is from btwilink.c. However, I can't see the > connection between Bluetooth (BLE) and UDP/IPv6 (we're not using > 6LoWPAN or anything similar). > > Thanks, Jacob Definitely these details are useful ;) Could you try : diff --git a/drivers/misc/ti-st/st_core.c b/drivers/misc/ti-st/st_core.c index 6e3af8b42cdd..0c99a74fb895 100644 --- a/drivers/misc/ti-st/st_core.c +++ b/drivers/misc/ti-st/st_core.c @@ -912,7 +912,9 @@ void st_core_exit(struct st_data_s *st_gdata) skb_queue_purge(&st_gdata->txq); skb_queue_purge(&st_gdata->tx_waitq); kfree_skb(st_gdata->rx_skb); + st_gdata->rx_skb = NULL; kfree_skb(st_gdata->tx_skb); + st_gdata->tx_skb = NULL; /* TTY ldisc cleanup */ err = tty_unregister_ldisc(N_TI_WL); if (err)