From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33518) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1alv4g-0003IW-ON for qemu-devel@nongnu.org; Fri, 01 Apr 2016 05:09:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1alv4a-0005k6-OQ for qemu-devel@nongnu.org; Fri, 01 Apr 2016 05:09:02 -0400 Received: from [59.151.112.132] (port=56256 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1alv4Z-0005fp-Ca for qemu-devel@nongnu.org; Fri, 01 Apr 2016 05:08:56 -0400 References: <1459494489-3532-1-git-send-email-zhang.zhanghailiang@huawei.com> <56FE25B2.7000203@redhat.com> <56FE3025.4010902@huawei.com> From: Wen Congyang Message-ID: <56FE3AE8.6060109@cn.fujitsu.com> Date: Fri, 1 Apr 2016 17:10:00 +0800 MIME-Version: 1.0 In-Reply-To: <56FE3025.4010902@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: Hailiang Zhang , Jason Wang , qemu-devel@nongnu.org Cc: peter.huangpeng@huawei.com On 04/01/2016 04:24 PM, Hailiang Zhang wrote: > On 2016/4/1 15:39, Jason Wang wrote: >> >> >> 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). >> > > Yes ~ > >> How about not call status_changed() if the initialization is not done? >> > > But seems that it is difficult to confirm if the filter is initialized > or not ... If nfc->setup() is not called, nf->netdev is NULL. Thanks Wen Congyang > >> . >> > > > > >