[Intel-gfx] [PATCH] drm/i915: Fix possible null dereference in framebuffer_info debugfs function

[Namrta Salonie]

Found by static code analysis tool.

v2: Inserted block instead of goto & renamed variables (Chris)

Signed-off-by: Namrta Salonie <namrta.salonie at intel.com>
Signed-off-by: Deepak S <deepak.s at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c |   32 +++++++++++++++-----------------
 1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index a3b22bd..7c068ea 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1865,31 +1865,29 @@ static int i915_gem_framebuffer_info(struct seq_file *m, void *data)
 {
 	struct drm_info_node *node = m->private;
 	struct drm_device *dev = node->minor->dev;
-	struct intel_fbdev *ifbdev = NULL;
-	struct intel_framebuffer *fb;
+	struct intel_framebuffer *fbdev_fb = NULL;
 	struct drm_framebuffer *drm_fb;
 
 #ifdef CONFIG_DRM_FBDEV_EMULATION
-	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 (to_i915(dev)->fbdev) {
+		fbdev_fb = to_intel_framebuffer(to_i915(dev)->fbdev->helper.fb);
+		seq_printf(m, "fbcon size: %d x %d, depth %d, %d bpp, modifier 0x%llx, refcount %d, obj ",
+				fbdev_fb->base.width,
+				fbdev_fb->base.height,
+				fbdev_fb->base.depth,
+				fbdev_fb->base.bits_per_pixel,
+				fbdev_fb->base.modifier[0],
+				atomic_read(&fbdev_fb->base.refcount.refcount));
+		describe_obj(m, fbdev_fb->obj);
+		seq_putc(m, '\n');
+	}
 #endif
 
 	mutex_lock(&dev->mode_config.fb_lock);
 	drm_for_each_fb(drm_fb, dev) {
-		fb = to_intel_framebuffer(drm_fb);
-		if (ifbdev && &fb->base == ifbdev->helper.fb)
+		struct intel_framebuffer *fb = to_intel_framebuffer(drm_fb);
+		if (fb == fbdev_fb)
 			continue;
 
 		seq_printf(m, "user size: %d x %d, depth %d, %d bpp, modifier 0x%llx, refcount %d, obj ",
-- 
1.7.9.5