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drm/i915: Fix oops caused by fbdev initialization failure 

intelfb_create() is called once on driver initialization. If it fails,
ifbdev->helper.fbdev, ifbdev->fb or ifbdev->fb->obj may be NULL.

Further up in the call stack, intel_fbdev_initial_config() calls
intel_fbdev_fini() to tear down the ifbdev on failure. This calls
intel_fbdev_destroy() which dereferences ifbdev->fb. Fix the ensuing
oops.

Also check in these functions if ifbdev is not NULL to avoid oops:

i915_gem_framebuffer_info() is called on access to debugfs file
"i915_gem_framebuffer" and dereferences ifbdev, ifbdev->helper.fb
and ifbdev->helper.fb->obj.

intel_connector_add_to_fbdev() / intel_connector_remove_from_fbdev()
are called when registering / unregistering an mst connector and
dereference ifbdev.

v3: Drop additional null pointer checks in intel_fbdev_set_suspend(),
    intel_fbdev_output_poll_changed() and intel_fbdev_restore_mode()
    since they already check if ifbdev is not NULL, which is sufficient
    now that intel_fbdev_fini() is called on initialization failure.
    (Requested by Daniel Vetter <daniel.vetter@ffwll.ch>)

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: http://patchwork.freedesktop.org/patch/msgid/d05f0edf121264a9d0adb8ca713fd8cc4ae068bf.1447938059.git.lukas@wunner.de
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Lukas Wunner 2015-11-18 13:43:20 +01:00 committed by Daniel Vetter
parent ce7f172856
commit 54632abe8c
3 changed files with 24 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
drivers/gpu/drm/i915/i915_debugfs.c
View File

@ -1878,17 +1878,19 @@ static int i915_gem_framebuffer_info(struct seq_file *m, void *data)
struct drm_i915_private *dev_priv = dev->dev_private;
ifbdev = dev_priv->fbdev;
fb = to_intel_framebuffer(ifbdev->helper.fb);
if (ifbdev) {
fb = to_intel_framebuffer(ifbdev->helper.fb);
seq_printf(m, "fbcon size: %d x %d, depth %d, %d bpp, modifier 0x%llx, refcount %d, obj ",
fb->base.width,
fb->base.height,
fb->base.depth,
fb->base.bits_per_pixel,
fb->base.modifier[0],
atomic_read(&fb->base.refcount.refcount));
describe_obj(m, fb->obj);
seq_putc(m, '\n');
seq_printf(m, "fbcon size: %d x %d, depth %d, %d bpp, modifier 0x%llx, refcount %d, obj ",
fb->base.width,
fb->base.height,
fb->base.depth,
fb->base.bits_per_pixel,
fb->base.modifier[0],
atomic_read(&fb->base.refcount.refcount));
describe_obj(m, fb->obj);
seq_putc(m, '\n');
}
#endif
mutex_lock(&dev->mode_config.fb_lock);

10
drivers/gpu/drm/i915/intel_dp_mst.c
View File

@ -408,7 +408,10 @@ static void intel_connector_add_to_fbdev(struct intel_connector *connector)
{
#ifdef CONFIG_DRM_FBDEV_EMULATION
struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
drm_fb_helper_add_one_connector(&dev_priv->fbdev->helper, &connector->base);
if (dev_priv->fbdev)
drm_fb_helper_add_one_connector(&dev_priv->fbdev->helper,
&connector->base);
#endif
}
@ -416,7 +419,10 @@ static void intel_connector_remove_from_fbdev(struct intel_connector *connector)
{
#ifdef CONFIG_DRM_FBDEV_EMULATION
struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
drm_fb_helper_remove_one_connector(&dev_priv->fbdev->helper, &connector->base);
if (dev_priv->fbdev)
drm_fb_helper_remove_one_connector(&dev_priv->fbdev->helper,
&connector->base);
#endif
}

6
drivers/gpu/drm/i915/intel_fbdev.c
View File

@ -529,8 +529,10 @@ static void intel_fbdev_destroy(struct drm_device *dev,
drm_fb_helper_fini(&ifbdev->helper);
drm_framebuffer_unregister_private(&ifbdev->fb->base);
drm_framebuffer_remove(&ifbdev->fb->base);
if (ifbdev->fb) {
drm_framebuffer_unregister_private(&ifbdev->fb->base);
drm_framebuffer_remove(&ifbdev->fb->base);
}
}
/*