Re: [PATCH v2] remote-viewer: fix free on dangling pointer

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On 9/30/19 5:08 AM, Victor Toso wrote:
From: Victor Toso <me@xxxxxxxxxxxxxx>

On remote_viewer_session_connected() we are passing a dup of URI of
connection and freeing it afterwards. Problem is, we don't disconnect
from listening "session-connected" and on an eventual second emission
of this signal, remote-viewer crashes as seen in the backtrace below.

This can happen over switch-host migration message from
SpiceMainChannel.

To fix the issue, use VirtViewerApp URI information instead of passing
a dup char*. The other changes in this patch were warnings of unused
variables.

Found it while improving migrate.py from spice/tests (server):
  | Invalid free() / delete / delete[] / realloc()
  |    at 0x4839A0C: free (vg_replace_malloc.c:540)
  |    by 0x56EBD8C: g_free (in /usr/lib64/libglib-2.0.so.0.6000.6)
  |    by 0x11DED0: remote_viewer_session_connected (remote-viewer.c:658)
  |    by 0x564D741: g_closure_invoke (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x56614F3: ??? (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566A34D: g_signal_emit_valist (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566AF68: g_signal_emit_by_name (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x135E5D: virt_viewer_session_spice_main_channel_event (virt-viewer-session-spice.c:699)
  |    by 0x564D741: g_closure_invoke (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x56614F3: ??? (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566A34D: g_signal_emit_valist (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x53149E3: emit_main_context (gio-coroutine.c:198)
  |  Address 0x18f1ecc0 is 0 bytes inside a block of size 23 free'd
  |    at 0x4839A0C: free (vg_replace_malloc.c:540)
  |    by 0x56EBD8C: g_free (in /usr/lib64/libglib-2.0.so.0.6000.6)
  |    by 0x11DED0: remote_viewer_session_connected (remote-viewer.c:658)
  |    by 0x564D741: g_closure_invoke (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x56614F3: ??? (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566A34D: g_signal_emit_valist (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566AF68: g_signal_emit_by_name (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x135E5D: virt_viewer_session_spice_main_channel_event (virt-viewer-session-spice.c:699)
  |    by 0x564D741: g_closure_invoke (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x56614F3: ??? (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566A34D: g_signal_emit_valist (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x53149E3: emit_main_context (gio-coroutine.c:198)
  |  Block was alloc'd at
  |    at 0x483880B: malloc (vg_replace_malloc.c:309)
  |    by 0x56EBC98: g_malloc (in /usr/lib64/libglib-2.0.so.0.6000.6)
  |    by 0x5705C43: g_strdup (in /usr/lib64/libglib-2.0.so.0.6000.6)
  |    by 0x11EB80: remote_viewer_initial_connect (remote-viewer.c:696)
  |    by 0x11EB80: remote_viewer_start (remote-viewer.c:790)
  |    by 0x1250D3: virt_viewer_app_start (virt-viewer-app.c:1727)
  |    by 0x127108: virt_viewer_app_on_application_startup (virt-viewer-app.c:1870)
  |    by 0x564D741: g_closure_invoke (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x5661638: ??? (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566A34D: g_signal_emit_valist (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x566A972: g_signal_emit (in /usr/lib64/libgobject-2.0.so.0.6000.6)
  |    by 0x553ECA1: g_application_register (in /usr/lib64/libgio-2.0.so.0.6000.6)
  |    by 0x553F41D: g_application_run (in /usr/lib64/libgio-2.0.so.0.6000.6)

Signed-off-by: Victor Toso <victortoso@xxxxxxxxxx>
---
  src/remote-viewer.c | 18 ++++++++++--------
  1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/remote-viewer.c b/src/remote-viewer.c
index 8938ef9..7cad231 100644
--- a/src/remote-viewer.c
+++ b/src/remote-viewer.c
@@ -396,7 +396,7 @@ virt_viewer_app_set_ovirt_foreign_menu(VirtViewerApp *app,
  }
static gboolean
-create_ovirt_session(VirtViewerApp *app, const char *uri, GError **err)
+create_ovirt_session(VirtViewerApp *app, GError **err)
  {
      OvirtProxy *proxy = NULL;
      OvirtApi *api = NULL;
@@ -421,9 +421,11 @@ create_ovirt_session(VirtViewerApp *app, const char *uri, GError **err)
      gchar *ticket = NULL;
      gchar *host_subject = NULL;
      gchar *guid = NULL;
+    gchar *uri = NULL;
g_return_val_if_fail(VIRT_VIEWER_IS_APP(app), FALSE); + g_object_get(app, "guri", &uri, NULL);
      if (!parse_ovirt_uri(uri, &rest_uri, &vm_name, &username)) {
          g_set_error_literal(&error, VIRT_VIEWER_ERROR, VIRT_VIEWER_ERROR_FAILED,
                              _("failed to parse ovirt uri"));
@@ -561,6 +563,7 @@ create_ovirt_session(VirtViewerApp *app, const char *uri, GError **err)
      success = TRUE;
error:
+    g_free(uri);
      g_free(username);
      g_free(rest_uri);
      g_free(vm_name);
@@ -645,17 +648,16 @@ remote_viewer_recent_add(gchar *uri, const gchar *mime_type)
static void
  remote_viewer_session_connected(VirtViewerSession *session,
-                                gchar *guri)
+                                VirtViewerApp *app)
  {
      gchar *uri = virt_viewer_session_get_uri(session);
      const gchar *mime = virt_viewer_session_mime_type(session);
if (uri == NULL)
-        uri = g_strdup(guri);
+        g_object_get(app, "guri", &uri, NULL);
remote_viewer_recent_add(uri, mime);
      g_free(uri);
-    g_free(guri);
  }

Patch builds now, but I started getting some warning when connecting to ovirt:// uri.

(remote-viewer:16940): virt-viewer-CRITICAL **: 11:00:14.560: remote_viewer_recent_add: assertion 'uri != NULL' failed


static gchar *
@@ -675,14 +677,14 @@ read_all_stdin(gsize *len, GError **err)
  }
static gboolean
-remote_viewer_initial_connect(RemoteViewer *self, const gchar *type, const gchar *guri,
+remote_viewer_initial_connect(RemoteViewer *self, const gchar *type,
                                VirtViewerFile *vvfile, GError **error)
  {
      VirtViewerApp *app = VIRT_VIEWER_APP(self);
#ifdef HAVE_OVIRT
      if (g_strcmp0(type, "ovirt") == 0) {
-        if (!create_ovirt_session(app, guri, error)) {
+        if (!create_ovirt_session(app, error)) {
              g_prefix_error(error, _("Couldn't open oVirt session: "));
              return FALSE;
          }
@@ -694,7 +696,7 @@ remote_viewer_initial_connect(RemoteViewer *self, const gchar *type, const gchar
      }
g_signal_connect(virt_viewer_app_get_session(app), "session-connected",
-                     G_CALLBACK(remote_viewer_session_connected), g_strdup(guri));
+                     G_CALLBACK(remote_viewer_session_connected), app);
virt_viewer_session_set_file(virt_viewer_app_get_session(app), vvfile);
  #ifdef HAVE_OVIRT
@@ -787,7 +789,7 @@ retry_dialog:
                                  _("Cannot determine the connection type from URI"));
              goto cleanup;
          }
-        if (!remote_viewer_initial_connect(self, type, guri, vvfile, &error))
+        if (!remote_viewer_initial_connect(self, type, vvfile, &error))
              goto cleanup;
      }


--
Eduardo de Barros Lima (Etrunko)
Software Engineer - Red Hat
etrunko@xxxxxxxxxx

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