From 255146e4a3d16c74390f8fdd6cae46b5d0d59ad5 Mon Sep 17 00:00:00 2001

From: Iain Lane <iainl@gnome.org>

Date: Fri, 10 Aug 2018 09:46:51 +0000

Subject: [PATCH 1/2] gpu-kms: Handle drmModeGetResources() failing

Avoid dereferencing the NULL return value if it fails. We still create

the MetaGpu, but we treat it as if it has no outputs.

Closes: https://gitlab.gnome.org/GNOME/mutter/issues/223

(cherry picked from commit 29cc526e2eab65d856d1fd0a652f22dcdb5d72dd)

---

 src/backends/native/meta-gpu-kms.c | 36 +++++++++++++++++++++++++-----

 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/src/backends/native/meta-gpu-kms.c b/src/backends/native/meta-gpu-kms.c

index 1d1c28809..7e7607c46 100644

--- a/src/backends/native/meta-gpu-kms.c

+++ b/src/backends/native/meta-gpu-kms.c

@@ -62,6 +62,8 @@ struct _MetaGpuKms

   int max_buffer_height;

   gboolean page_flips_not_supported;

+

+  gboolean resources_init_failed_before;

 };

 G_DEFINE_QUARK (MetaGpuKmsError, meta_gpu_kms_error)

@@ -709,20 +711,34 @@ init_outputs (MetaGpuKms       *gpu_kms,

   setup_output_clones (gpu);

 }

-static void

-meta_kms_resources_init (MetaKmsResources *resources,

-                         int               fd)

+static gboolean

+meta_kms_resources_init (MetaKmsResources  *resources,

+                         int                fd,

+                         GError           **error)

+

 {

   drmModeRes *drm_resources;

   unsigned int i;

   drm_resources = drmModeGetResources (fd);

+

+  if (!drm_resources)

+    {

+      g_set_error (error,

+                   G_IO_ERROR,

+                   G_IO_ERROR_FAILED,

+                   "Calling drmModeGetResources() failed");

+      return FALSE;

+    }

+

   resources->resources = drm_resources;

   resources->n_encoders = (unsigned int) drm_resources->count_encoders;

   resources->encoders = g_new (drmModeEncoder *, resources->n_encoders);

   for (i = 0; i < resources->n_encoders; i++)

     resources->encoders[i] = drmModeGetEncoder (fd, drm_resources->encoders[i]);

+

+  return TRUE;

 }

 static void

@@ -734,7 +750,7 @@ meta_kms_resources_release (MetaKmsResources *resources)

     drmModeFreeEncoder (resources->encoders[i]);

   g_free (resources->encoders);

-  drmModeFreeResources (resources->resources);

+  g_clear_pointer (&resources->resources, drmModeFreeResources);

 }

 static gboolean

@@ -745,8 +761,18 @@ meta_gpu_kms_read_current (MetaGpu  *gpu,

   MetaMonitorManager *monitor_manager =

     meta_gpu_get_monitor_manager (gpu);

   MetaKmsResources resources;

+  g_autoptr (GError) local_error = NULL;

-  meta_kms_resources_init (&resources, gpu_kms->fd);

+  if (!meta_kms_resources_init (&resources, gpu_kms->fd, &local_error))

+    {

+      if (!gpu_kms->resources_init_failed_before)

+        {

+          g_warning ("meta_kms_resources_init failed: %s, assuming we have no outputs",

+                     local_error->message);

+          gpu_kms->resources_init_failed_before = TRUE;

+        }

+      return TRUE;

+    }

   gpu_kms->max_buffer_width = resources.resources->max_width;

   gpu_kms->max_buffer_height = resources.resources->max_height;

-- 

2.19.0