From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:54487) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QZEuh-0004re-En for qemu-devel@nongnu.org; Wed, 22 Jun 2011 00:19:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QZEug-00051v-9v for qemu-devel@nongnu.org; Wed, 22 Jun 2011 00:19:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38696) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QZEug-00051o-17 for qemu-devel@nongnu.org; Wed, 22 Jun 2011 00:19:38 -0400 Date: Wed, 22 Jun 2011 09:49:22 +0530 From: Amit Shah Message-ID: <20110622041922.GA5789@amit-x200.redhat.com> References: <20110617155808.0f080bfc@doriath> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110617155808.0f080bfc@doriath> Subject: Re: [Qemu-devel] [PATCH v2] virtio-serial: Fix segfault on guest boot List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: qemu-devel , mdroth@linux.vnet.ibm.com, Markus Armbruster On (Fri) 17 Jun 2011 [15:58:08], Luiz Capitulino wrote: > If I start qemu with: > > # qemu -hda disks/test.img -enable-kvm -m 1G -snapshot \ > -device virtio-serial \ > -chardev socket,host=localhost,port=1234,server,nowait,id=foo \ > -device virtserialport,chardev=foo,name=org.qemu.guest_agent > > I get a segfault when booting a Fedora 14 guest. The backtrace says: > > Program terminated with signal 11, Segmentation fault. > #0 0x0000000000420850 in handle_control_message (vser=0x3732bd0, buf=0x2c173e0, len=8) at /home/lcapitulino/src/qmp-unstable/hw/virtio-serial-bus.c:335 > 335 info = DO_UPCAST(VirtIOSerialPortInfo, qdev, port->dev.info); > > What's happening is VIRTIO_CONSOLE_DEVICE_READY is a message for the > whole device, not for an individual port. So port is NULL. This bug was > introduced by commit a15bb0d6a981de749452a5180fc8084d625671da. > > This commit fixes that by making the port returned by find_port_by_id() > be used only by the VIRTIO_CONSOLE_PORT_READY and > VIRTIO_CONSOLE_PORT_OPEN messages. > > Signed-off-by: Luiz Capitulino > --- > hw/virtio-serial-bus.c | 24 ++++++++++++++---------- > 1 files changed, 14 insertions(+), 10 deletions(-) > > diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c > index 9a12104..33a6f61 100644 > --- a/hw/virtio-serial-bus.c > +++ b/hw/virtio-serial-bus.c > @@ -328,18 +328,11 @@ static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len) > cpkt.event = lduw_p(&gcpkt->event); > cpkt.value = lduw_p(&gcpkt->value); > > - port = find_port_by_id(vser, ldl_p(&gcpkt->id)); > - if (!port && cpkt.event != VIRTIO_CONSOLE_DEVICE_READY) > - return; > - > - info = DO_UPCAST(VirtIOSerialPortInfo, qdev, port->dev.info); > - > - switch(cpkt.event) { > - case VIRTIO_CONSOLE_DEVICE_READY: > + if (cpkt.event == VIRTIO_CONSOLE_DEVICE_READY) { What we lose after this re-arrangement is the check that port is NULL when this message is received. i.e., a guest bug where port is set to a valid value when this message arrives. (I think I pointed this out in a previous mail?) > if (!cpkt.value) { > error_report("virtio-serial-bus: Guest failure in adding device %s\n", > vser->bus.qbus.name); > - break; > + return; > } > /* > * The device is up, we can now tell the device about all the > @@ -348,8 +341,19 @@ static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len) > QTAILQ_FOREACH(port, &vser->ports, next) { > send_control_event(port, VIRTIO_CONSOLE_PORT_ADD, 1); > } > - break; > + return; > + } > > + port = find_port_by_id(vser, ldl_p(&gcpkt->id)); > + if (!port) { > + error_report("virtio-serial-bus: Expected port id %d for device %s\n", > + ldl_p(&gcpkt->id), vser->bus.qbus.name); It's actually 'unexpected port id...' :-) Also, port id is %u, not %d. Fixed these two and committed to virtio-serial tree. Thanks, Amit