From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43448) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1altgA-0005BV-KT for qemu-devel@nongnu.org; Fri, 01 Apr 2016 03:39:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1altg7-0003Yv-EE for qemu-devel@nongnu.org; Fri, 01 Apr 2016 03:39:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49779) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1altg7-0003Yr-9B for qemu-devel@nongnu.org; Fri, 01 Apr 2016 03:39:35 -0400 References: <1459494489-3532-1-git-send-email-zhang.zhanghailiang@huawei.com> From: Jason Wang Message-ID: <56FE25B2.7000203@redhat.com> Date: Fri, 1 Apr 2016 15:39:30 +0800 MIME-Version: 1.0 In-Reply-To: <1459494489-3532-1-git-send-email-zhang.zhanghailiang@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] filter-buffer: fix segfault while start qemu with status=off property List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: zhanghailiang , qemu-devel@nongnu.org On 04/01/2016 03:08 PM, zhanghailiang wrote: > After commit 338d3f, we support 'status' property for filter object. > The segfault can be triggered by starting qemu with 'status=off' property > for filter, when the s->incoming_queue is NULL, we reference it directly > in qemu_net_queue_flush(). > > Let's check the value of 's->incoming_queue' before calling > qemu_net_queue_flush(). > > Signed-off-by: zhanghailiang > --- > net/filter-buffer.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/filter-buffer.c b/net/filter-buffer.c > index cc6bd94..79e2ce3 100644 > --- a/net/filter-buffer.c > +++ b/net/filter-buffer.c > @@ -34,7 +34,7 @@ static void filter_buffer_flush(NetFilterState *nf) > { > FilterBufferState *s = FILTER_BUFFER(nf); > > - if (!qemu_net_queue_flush(s->incoming_queue)) { > + if (s->incoming_queue && !qemu_net_queue_flush(s->incoming_queue)) { > /* Unable to empty the queue, purge remaining packets */ > qemu_net_queue_purge(s->incoming_queue, nf->netdev); > } We'd better handle this at generic layer and don't let a specific net filter need to worry about this. Looks like the issue is we may trigger status_changed() too early (even before the the filter was initialized). How about not call status_changed() if the initialization is not done?