From 54632abe8ca3db8621673b186c7cc0e869c0032f Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Wed, 18 Nov 2015 13:43:20 +0100 Subject: [PATCH] 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 ) Signed-off-by: Lukas Wunner Link: http://patchwork.freedesktop.org/patch/msgid/d05f0edf121264a9d0adb8ca713fd8cc4ae068bf.1447938059.git.lukas@wunner.de Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_debugfs.c | 24 +++++++++++++----------- drivers/gpu/drm/i915/intel_dp_mst.c | 10 ++++++++-- drivers/gpu/drm/i915/intel_fbdev.c | 6 ++++-- 3 files changed, 25 insertions(+), 15 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index a9af884dadd5..08eb40292933 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -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); - - 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'); + 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'); + } #endif mutex_lock(&dev->mode_config.fb_lock); diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c index 8a604ac797aa..a12d1c7ee0e7 100644 --- a/drivers/gpu/drm/i915/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/intel_dp_mst.c @@ -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 } diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c index 98772d37b09f..cdbef32897f0 100644 --- a/drivers/gpu/drm/i915/intel_fbdev.c +++ b/drivers/gpu/drm/i915/intel_fbdev.c @@ -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); + } } /* -- 2.39.5