[PATCH v2] plugins/wifi: Fix GSupplicantInterface socket leak during teardown

[kasuta@riseup.net]

When a virtual or unmanaged wifi interface is dropped out-of-band, 
interface_removed() is invoked within the wireless event loop.

If the underlying wifi struct or its device linkage has already been 
cleared during a topology shift, the current logic bypasses the 
mandatory g_supplicant_interface_cancel() and data unreferencing 
routines due to missing fallback handling. This causes netlink and 
event file descriptors to permanently leak in the process table.

Refactor interface_removed() to ensure resource cancellation runs 
unconditionally, even if device pointers are already gone.

Signed-off-by: Doemela <kasuta@riseup.net>
---
diff --git a/plugins/wifi.c b/plugins/wifi.c
index d18dc6cd..df938c1a 100644
--- a/plugins/wifi.c
+++ b/plugins/wifi.c
@@ -2284,14 +2284,14 @@ static void
interface_removed(GSupplicantInterface *interface)
 
 	wifi = g_supplicant_interface_get_data(interface);
 
 	if (wifi)
 		wifi->interface = NULL;
 
 	if (wifi && wifi->tethering)
 		return;
 
-	if (wifi == NULL || wifi->device == NULL)
-		return;
-
-	connman_device_set_powered(wifi->device, FALSE);
+	if (wifi != NULL && wifi->device != NULL)
+		connman_device_set_powered(wifi->device, FALSE);
+
+	g_supplicant_interface_set_data(interface, NULL);
+	g_supplicant_interface_cancel(interface);
 }