drm/i915: Fix possible null dereference in framebuffer_info debugfs function

Found by static code analysis tool.

v2: Inserted block instead of goto & renamed variables (Chris)
v3: Aligned code as per the opening brace (Chris)
    Rebased on top of nightly (Daniel)

Signed-off-by: Namrta Salonie <namrta.salonie@intel.com>
Signed-off-by: Deepak S <deepak.s@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index a728ff1..bfd57fb 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1869,33 +1869,29 @@ 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;
-       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');
-       }
+       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 ",