[virt-tools-list] [remote-viewer v1] remote-viewer: fix free on dangling pointer

Victor Toso victortoso at redhat.com
Fri Sep 27 13:35:22 UTC 2019


From: Victor Toso <me at victortoso.com>

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 at redhat.com>
---
 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..2818221 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 *guri = NULL;
 
     g_return_val_if_fail(VIRT_VIEWER_IS_APP(app), FALSE);
 
+    g_object_get(app, "guri", &guri, 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(guri);
     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);
 }
 
 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;
     }
 
-- 
2.21.0




More information about the virt-tools-list mailing list