From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53055) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aluTM-00012x-Ej for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:30:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aluTI-0005cx-FI for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:30:28 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:54311) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aluTH-0005br-TJ for qemu-devel@nongnu.org; Fri, 01 Apr 2016 04:30:24 -0400 References: <1459494489-3532-1-git-send-email-zhang.zhanghailiang@huawei.com> <56FE25B2.7000203@redhat.com> From: Hailiang Zhang Message-ID: <56FE3025.4010902@huawei.com> Date: Fri, 1 Apr 2016 16:24:05 +0800 MIME-Version: 1.0 In-Reply-To: <56FE25B2.7000203@redhat.com> Content-Type: text/plain; charset="windows-1252"; format=flowed 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: Jason Wang , qemu-devel@nongnu.org Cc: peter.huangpeng@huawei.com 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 ... > . >