Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755543AbcKYQOi (ORCPT ); Fri, 25 Nov 2016 11:14:38 -0500 Received: from vps0.lunn.ch ([178.209.37.122]:55962 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755453AbcKYQOZ (ORCPT ); Fri, 25 Nov 2016 11:14:25 -0500 Date: Fri, 25 Nov 2016 17:14:15 +0100 From: Andrew Lunn To: Nikita Yushchenko Cc: Vivien Didelot , Florian Fainelli , "David S. Miller" , John Crispin , Wei Yongjun , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Healy Subject: Re: [PATCH] net: dsa: fix unbalanced dsa_switch_tree reference counting Message-ID: <20161125161415.GJ26806@lunn.ch> References: <1480090133-30412-1-git-send-email-nikita.yoush@cogentembedded.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1480090133-30412-1-git-send-email-nikita.yoush@cogentembedded.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1716 Lines: 55 On Fri, Nov 25, 2016 at 07:08:53PM +0300, Nikita Yushchenko wrote: > _dsa_register_switch() gets a dsa_switch_tree object either via > dsa_get_dst() or via dsa_add_dst(). Former path does not increase kref > in returned object (resulting into caller not owning a reference), > while later path does create a new object (resulting into caller owning > a reference). > > The rest of _dsa_register_switch() assumes that it owns a reference, and > calls dsa_put_dst(). > > This causes a memory breakage if first switch in the tree initialized > successfully, but second failed to initialize. In particular, freed > dsa_swith_tree object is left referenced by switch that was initialized, > and later access to sysfs attributes of that switch cause OOPS. > > To fix, need to add kref_get() call to dsa_get_dst(). > > Signed-off-by: Nikita Yushchenko Hi Nikita What tree is this against? It should be net. Please make the subject [patch net] ... so it is clear what tree this is for. And it should have a fixes-tag Fixes: 83c0afaec7b7 ("net: dsa: Add new binding implementation") Reviewed-by: Andrew Lunn Andrew > --- > net/dsa/dsa2.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c > index f8a7d9aab437..5fff951a0a49 100644 > --- a/net/dsa/dsa2.c > +++ b/net/dsa/dsa2.c > @@ -28,8 +28,10 @@ static struct dsa_switch_tree *dsa_get_dst(u32 tree) > struct dsa_switch_tree *dst; > > list_for_each_entry(dst, &dsa_switch_trees, list) > - if (dst->tree == tree) > + if (dst->tree == tree) { > + kref_get(&dst->refcount); > return dst; > + } > return NULL; > } > > -- > 2.1.4 >