[Spice-devel] [spice-gtk v2 1/2] channel-usbredir: Fix crash on channel-up

[Christophe Fergeau]

On Thu, Dec 01, 2016 at 02:20:29PM +0100, Victor Toso wrote:
> Hi,
> 
> On Thu, Dec 01, 2016 at 01:29:50PM +0100, Christophe Fergeau wrote:
> > On Wed, Nov 30, 2016 at 06:36:32PM +0100, Victor Toso wrote:
> > > From: Victor Toso <me at victortoso.com>
> > > 
> > > SpiceSession does not initialize its SpiceUsbDeviceManager object on
> > > startup that could lead to a race condition where channel-usbredir is
> > > requested to flush data while it is uninitialized.
> > > 
> > > In a few places, spice_usb_device_manager_get() is called as in
> > > usb-device-widget.c and spice-gtk-session.c but not used in
> > > spicy-stats, making the tool to crash on startup.
> > 
> > Just running spicy-stats when there is a usbredir channel is going to
> > cause a crash?
> 
> Yes

Ok, I'd mention this explicitly "making the tool crash on startup if
it encounters an usbredir channel"

> 
> > Isn't this avoided by your next patch as well
> 
> Yes
> 
> > which makes sure host is not NULL before trying to flush?
> 
> I see this as two different problems, really.
> 
> 1-) chanel-usbredir should take in consideration that it might not be
>     initialized (second patch)
> 2-) SpiceSession should initialize SpiceUsbDeviceManager (this patch)
>     otherwise, situations like (1) could happen;
> 
> spice_usb_device_manager_initable_init() could fail here so, the
> situation in (1) might as well happen.
> 
> > 
> > Christophe
> > 
> > > 
> > >  #0 in usbredirhost_write_guest_data (host=0x0) at usbredir/usbredirhost/usbredirhost.c:876
> > >  #1 in spice_usbredir_channel_up (c=0x643830) at channel-usbredir.c:821
> > >  #2 in spice_channel_up (channel=0x643830) at spice-channel.c:1238
> > >  #3 in spice_channel_recv_auth (channel=0x643830) at spice-channel.c:1225
> > >  #4 in spice_channel_coroutine (data=0x643830) at spice-channel.c:2580
> > >  #5 in coroutine_trampoline (cc=0x642ec0) at coroutine_ucontext.c:63
> > >  #6 in continuation_trampoline (i0=6565568, i1=0) at continuation.c:55
> > > 
> > > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1399838
> > > 
> > > Signed-off-by: Victor Toso <victortoso at redhat.com>
> > > Reported-by: Michael Cullen <michael at cullen-online.com>
> > > ---
> > >  src/spice-session.c | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > > 
> > > diff --git a/src/spice-session.c b/src/spice-session.c
> > > index f900bd1..91e4f97 100644
> > > --- a/src/spice-session.c
> > > +++ b/src/spice-session.c
> > > @@ -281,6 +281,7 @@ static void spice_session_init(SpiceSession *session)
> > >  {
> > >      SpiceSessionPrivate *s;
> > >      gchar *channels;
> > > +    GError *err = NULL;
> > >  
> > >      SPICE_DEBUG("New session (compiled from package " PACKAGE_STRING ")");
> > >      s = session->priv = SPICE_SESSION_GET_PRIVATE(session);
> > > @@ -293,6 +294,12 @@ static void spice_session_init(SpiceSession *session)
> > >      s->images = cache_image_new((GDestroyNotify)pixman_image_unref);
> > >      s->glz_window = glz_decoder_window_new();
> > >      update_proxy(session, NULL);
> > > +
> > > +    spice_usb_device_manager_get(session, &err);

I know this is going to be redundant, but
session->priv->usb_manager = spice_usb_device_manager_get(session, &err);
would look a bit better.

Either way,
Acked-by: Christophe Fergeau <cfergeau at redhat.com>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 801 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/spice-devel/attachments/20161201/956c1141/attachment.sig>