ui/win32: fix potential use-after-free with dbus shared memory

DisplaySurface may be free before the pixman image is freed, since the
image is refcounted and used by different objects, including pending
dbus messages.

Furthermore, setting the destroy function in
create_displaysurface_from() isn't appropriate, as it may not be used,
and may be overriden as in ramfb.

Set the destroy function when the shared handle is set, use the HANDLE
directly for destroy data, using a single common helper
qemu_pixman_win32_image_destroy().

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20241008125028.1177932-5-marcandre.lureau@redhat.com>
(cherry picked from commit 330ef31deb2e5461cff907488b710f5bd9cd2327)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index a7b16ba072ed96f840494d7cb987ec59fc15ca8a..746160a17584242d6dcef801870d0dc497d09484 100644 (file)
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -239,16 +239,6 @@ static uint32_t calc_image_hostmem(pixman_format_code_t pformat,
     return height * stride;
 }
 
-#ifdef WIN32
-static void
-win32_pixman_image_destroy(pixman_image_t *image, void *data)
-{
-    HANDLE handle = data;
-
-    qemu_win32_map_free(pixman_image_get_data(image), handle, &error_warn);
-}
-#endif
-
 static void virtio_gpu_resource_create_2d(VirtIOGPU *g,
                                           struct virtio_gpu_ctrl_command *cmd)
 {
@@ -309,7 +299,7 @@ static void virtio_gpu_resource_create_2d(VirtIOGPU *g,
             bits, c2d.height ? res->hostmem / c2d.height : 0);
 #ifdef WIN32
         if (res->image) {
-            pixman_image_set_destroy_function(res->image, win32_pixman_image_destroy, res->handle);
+            pixman_image_set_destroy_function(res->image, qemu_pixman_win32_image_destroy, res->handle);
         }
 #endif
     }
@@ -1303,7 +1293,7 @@ static int virtio_gpu_load(QEMUFile *f, void *opaque, size_t size,
             return -EINVAL;
         }
 #ifdef WIN32
-        pixman_image_set_destroy_function(res->image, win32_pixman_image_destroy, res->handle);
+        pixman_image_set_destroy_function(res->image, qemu_pixman_win32_image_destroy, res->handle);
 #endif
 
         res->addrs = g_new(uint64_t, res->iov_cnt);

diff --git a/include/ui/qemu-pixman.h b/include/ui/qemu-pixman.h
index ef13a8210cc4a9a2997a9f4a3712db69c235647e..e3dd72b9e388206c3239c0d8e15851553f1274f0 100644 (file)
--- a/include/ui/qemu-pixman.h
+++ b/include/ui/qemu-pixman.h
@@ -97,6 +97,8 @@ void qemu_pixman_glyph_render(pixman_image_t *glyph,
 
 void qemu_pixman_image_unref(pixman_image_t *image);
 
+void qemu_pixman_win32_image_destroy(pixman_image_t *image, void *data);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(pixman_image_t, qemu_pixman_image_unref)
 
 #endif /* QEMU_PIXMAN_H */

diff --git a/ui/console.c b/ui/console.c
index 832055675c50e48f3e2addb4be6db40e0ee83615..c462b8f2280415321462c8a0c730d332e2b1025c 100644 (file)
--- a/ui/console.c
+++ b/ui/console.c
@@ -504,24 +504,6 @@ void qemu_displaysurface_win32_set_handle(DisplaySurface *surface,
     surface->handle = h;
     surface->handle_offset = offset;
 }
-
-static void
-win32_pixman_image_destroy(pixman_image_t *image, void *data)
-{
-    DisplaySurface *surface = data;
-
-    if (!surface->handle) {
-        return;
-    }
-
-    assert(surface->handle_offset == 0);
-
-    qemu_win32_map_free(
-        pixman_image_get_data(surface->image),
-        surface->handle,
-        &error_warn
-    );
-}
 #endif
 
 DisplaySurface *qemu_create_displaysurface(int width, int height)
@@ -547,6 +529,8 @@ DisplaySurface *qemu_create_displaysurface(int width, int height)
 
 #ifdef WIN32
     qemu_displaysurface_win32_set_handle(surface, handle, 0);
+    pixman_image_set_destroy_function(surface->image,
+                                      qemu_pixman_win32_image_destroy, handle);
 #endif
     return surface;
 }
@@ -562,10 +546,6 @@ DisplaySurface *qemu_create_displaysurface_from(int width, int height,
                                               width, height,
                                               (void *)data, linesize);
     assert(surface->image != NULL);
-#ifdef WIN32
-    pixman_image_set_destroy_function(surface->image,
-                                      win32_pixman_image_destroy, surface);
-#endif
 
     return surface;
 }

diff --git a/ui/qemu-pixman.c b/ui/qemu-pixman.c
index 5ca55dd19984969ec113fb9d8b105f33e7f4632a..de6c88151c20e74493f4b90543e95ff103f2f82f 100644 (file)
--- a/ui/qemu-pixman.c
+++ b/ui/qemu-pixman.c
@@ -4,6 +4,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qapi/error.h"
 #include "ui/console.h"
 #include "standard-headers/drm/drm_fourcc.h"
 #include "trace.h"
@@ -268,3 +269,17 @@ void qemu_pixman_glyph_render(pixman_image_t *glyph,
     pixman_image_unref(ibg);
 }
 #endif /* CONFIG_PIXMAN */
+
+#ifdef WIN32
+void
+qemu_pixman_win32_image_destroy(pixman_image_t *image, void *data)
+{
+    HANDLE handle = data;
+
+    qemu_win32_map_free(
+        pixman_image_get_data(image),
+        handle,
+        &error_warn
+    );
+}
+#endif