Return-Path: Message-ID: <1418991279.9848.6.camel@jrissane-mobl.ger.corp.intel.com> Subject: Re: [PATCH] Bluetooth: 6lowpan: Do not free skb when packet is dropped From: Jukka Rissanen To: Marcel Holtmann Cc: linux-bluetooth@vger.kernel.org Date: Fri, 19 Dec 2014 14:14:39 +0200 In-Reply-To: <682DAC14-BA0D-4BEC-8709-4F4D2364FA62@holtmann.org> References: <1418213993-24884-1-git-send-email-jukka.rissanen@linux.intel.com> <1418911535.2876.25.camel@jrissane-mobl.ger.corp.intel.com> <682DAC14-BA0D-4BEC-8709-4F4D2364FA62@holtmann.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-ID: Hi Marcel, On to, 2014-12-18 at 17:49 +0100, Marcel Holtmann wrote: > Hi Jukka, > > >> If we need to drop the message because of some error in the > >> compression etc, then do not free the skb as that is done > >> automatically in other part of networking stack. > >> > >> Signed-off-by: Jukka Rissanen > >> --- > >> net/bluetooth/6lowpan.c | 1 - > >> 1 file changed, 1 deletion(-) > >> > >> diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c > >> index bdcaefd..ca5b4ec 100644 > >> --- a/net/bluetooth/6lowpan.c > >> +++ b/net/bluetooth/6lowpan.c > >> @@ -390,7 +390,6 @@ static int recv_pkt(struct sk_buff *skb, struct net_device *dev, > >> > >> drop: > >> dev->stats.rx_dropped++; > >> - kfree_skb(skb); > >> return NET_RX_DROP; > >> } > >> > > > > > > This patch should be applied at least in bluetooth-next. I have not seen > > any errors in earlier kernels as we never seem to go to this branch but > > because of Alex's ip header compression patches (that are still > > pending), this error branch will be hit quite easily in the future. The > > patch could be applied also to earlier kernels just in case. > > are we talking about 3.19 candidate or 3.20 kernel? Any earlier kernel having BT 6lowpan is affected to this double free. The bug was introduced by commit 18722c24 dated a year ago. Alex's patch (introducing nhc framework) will trigger this bug more easily and it was proposed Dec 8, but because of some issues a new patch version is expected. Cheers, Jukka