[Spice-devel] [PATCH spice-gtk] usbredir: Check for existing usb channels after libusb init

[Hans de Goede]

Currently trying to view a usbredir enabled vm from virt-manager causes
virt-manager to crash. This crash is caused by the following happening:

-virt-manager sets up the session, including connecting all the channels
-a spice-gtk internal code path calls spice_usb_device_manager_get()
-spice_usb_device_manager_get calls channel_new on all already connected
 usb channels
-channel_new does:
 spice_usbredir_channel_set_context(SPICE_USBREDIR_CHANNEL(channel),
                                    self->priv->context);
-But self->priv->context has not been set yet (so is NULL) -> segfault!

This patch fixes this by moving the iterating over already connected
usb channels to after the setting of self->priv->context. Note this means
that the channels will no longer get checked when there is no USB_REDIR
support. That is not a problem since spice_usb_device_manager_initable_init
will return FALSE in that case anyways.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 gtk/usb-device-manager.c |   27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/gtk/usb-device-manager.c b/gtk/usb-device-manager.c
index 37cc88b..18d5bd5 100644
--- a/gtk/usb-device-manager.c
+++ b/gtk/usb-device-manager.c
@@ -147,11 +147,11 @@ static gboolean spice_usb_device_manager_initable_init(GInitable  *initable,
                                                     GCancellable  *cancellable,
                                                     GError        **err)
 {
-    GList *list;
-    GList *it;
     SpiceUsbDeviceManager *self;
     SpiceUsbDeviceManagerPrivate *priv;
 #ifdef USE_USBREDIR
+    GList *list;
+    GList *it;
     int rc;
     const gchar *const subsystems[] = {"usb", NULL};
 #endif
@@ -174,17 +174,8 @@ static gboolean spice_usb_device_manager_initable_init(GInitable  *initable,
         return FALSE;
     }
 
-    g_signal_connect(priv->session, "channel-new",
-                     G_CALLBACK(channel_new), self);
-    g_signal_connect(priv->session, "channel-destroy",
-                     G_CALLBACK(channel_destroy), self);
-    list = spice_session_get_channels(priv->session);
-    for (it = g_list_first(list); it != NULL; it = g_list_next(it)) {
-        channel_new(priv->session, it->data, (gpointer*)self);
-    }
-    g_list_free(list);
-
 #ifdef USE_USBREDIR
+    /* Initialize libusb */
     rc = libusb_init(&priv->context);
     if (rc < 0) {
         const char *desc = spice_usbutil_libusb_strerror(rc);
@@ -194,6 +185,18 @@ static gboolean spice_usb_device_manager_initable_init(GInitable  *initable,
         return FALSE;
     }
 
+    /* Start listening for usb channels connect/disconnect */
+    g_signal_connect(priv->session, "channel-new",
+                     G_CALLBACK(channel_new), self);
+    g_signal_connect(priv->session, "channel-destroy",
+                     G_CALLBACK(channel_destroy), self);
+    list = spice_session_get_channels(priv->session);
+    for (it = g_list_first(list); it != NULL; it = g_list_next(it)) {
+        channel_new(priv->session, it->data, (gpointer*)self);
+    }
+    g_list_free(list);
+
+    /* Start listening for usb devices plug / unplug */
     priv->udev = g_udev_client_new(subsystems);
     g_signal_connect(G_OBJECT(priv->udev), "uevent",
                      G_CALLBACK(spice_usb_device_manager_uevent_cb), self);
-- 
1.7.9.3