The patch below does not apply to the 4.13-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 15727ed0d944ce1dec8b9e1082dd3df29a0fdf44 Mon Sep 17 00:00:00 2001 From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Date: Thu, 22 Jun 2017 17:02:11 +0100 Subject: [PATCH] drm/i915/fbdev: Check for existence of ifbdev->vma before operations Commit fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer flushes") adds a dependency to ifbdev->vma when flushing the framebufer, but the checks are only against the existence of the ifbdev->fb and not against ifbdev->vma. This leaves a window of opportunity where we may try to operate on the fbdev prior to it being probed (thanks to asynchronous booting). Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101534 Fixes: fabef825626d ("drm/i915: Drop struct_mutex around frontbuffer flushes") Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/20170622160211.783-1-chris@xxxxxxxxxxxxxxxxxx Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c index 03347c6ae599..0c4cde6b2e6f 100644 --- a/drivers/gpu/drm/i915/intel_fbdev.c +++ b/drivers/gpu/drm/i915/intel_fbdev.c @@ -535,13 +535,14 @@ static void intel_fbdev_destroy(struct intel_fbdev *ifbdev) drm_fb_helper_fini(&ifbdev->helper); - if (ifbdev->fb) { + if (ifbdev->vma) { mutex_lock(&ifbdev->helper.dev->struct_mutex); intel_unpin_fb_vma(ifbdev->vma); mutex_unlock(&ifbdev->helper.dev->struct_mutex); + } + if (ifbdev->fb) drm_framebuffer_remove(&ifbdev->fb->base); - } kfree(ifbdev); } @@ -765,7 +766,7 @@ void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool synchronous struct intel_fbdev *ifbdev = dev_priv->fbdev; struct fb_info *info; - if (!ifbdev || !ifbdev->fb) + if (!ifbdev || !ifbdev->vma) return; info = ifbdev->helper.fbdev; @@ -812,7 +813,7 @@ void intel_fbdev_output_poll_changed(struct drm_device *dev) { struct intel_fbdev *ifbdev = to_i915(dev)->fbdev; - if (ifbdev && ifbdev->fb) + if (ifbdev && ifbdev->vma) drm_fb_helper_hotplug_event(&ifbdev->helper); } @@ -824,7 +825,7 @@ void intel_fbdev_restore_mode(struct drm_device *dev) return; intel_fbdev_sync(ifbdev); - if (!ifbdev->fb) + if (!ifbdev->vma) return; if (drm_fb_helper_restore_fbdev_mode_unlocked(&ifbdev->helper) == 0)