drivers/gpu/drm/i915/display/intel_color.c:1840 ilk_read_lut_8() error: potential null dereference 'blob'. (drm_property_create_blob returns null)

[kbuild test robot <lkp@intel.com>]

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   caffb99b6929f41a69edbb5aef3a359bf45f3315
commit: 100882673ab83b55ea0e9ed3ad301125d36039a3 drm/i915: Split i9xx_read_lut_8() to gmch vs. ilk variants
date:   3 months ago
config: i386-allyesconfig (attached as .config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build):
        git checkout 100882673ab83b55ea0e9ed3ad301125d36039a3
        # save the attached .config to linux build tree
        make ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>

New smatch warnings:
drivers/gpu/drm/i915/display/intel_color.c:1840 ilk_read_lut_8() error: potential null dereference 'blob'.  (drm_property_create_blob returns null)

Old smatch warnings:
drivers/gpu/drm/i915/display/intel_color.c:1706 i9xx_read_lut_8() error: potential null dereference 'blob'.  (drm_property_create_blob returns null)
drivers/gpu/drm/i915/display/intel_color.c:1747 i965_read_lut_10p6() error: potential null dereference 'blob'.  (drm_property_create_blob returns null)
drivers/gpu/drm/i915/display/intel_color.c:1799 chv_read_cgm_lut() error: potential null dereference 'blob'.  (drm_property_create_blob returns null)
drivers/gpu/drm/i915/display/intel_color.c:1873 ilk_read_lut_10() error: potential null dereference 'blob'.  (drm_property_create_blob returns null)
drivers/gpu/drm/i915/display/intel_color.c:1920 glk_read_lut_10() error: potential null dereference 'blob'.  (drm_property_create_blob returns null)

vim +/blob +1840 drivers/gpu/drm/i915/display/intel_color.c

  1823	
  1824	static struct drm_property_blob *
  1825	ilk_read_lut_8(const struct intel_crtc_state *crtc_state)
  1826	{
  1827		struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
  1828		struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
  1829		enum pipe pipe = crtc->pipe;
  1830		struct drm_property_blob *blob;
  1831		struct drm_color_lut *blob_data;
  1832		u32 i, val;
  1833	
  1834		blob = drm_property_create_blob(&dev_priv->drm,
  1835						sizeof(struct drm_color_lut) * LEGACY_LUT_LENGTH,
  1836						NULL);
  1837		if (IS_ERR(blob))
  1838			return NULL;
  1839	
> 1840		blob_data = blob->data;
  1841	
  1842		for (i = 0; i < LEGACY_LUT_LENGTH; i++) {
  1843			val = intel_de_read(dev_priv, LGC_PALETTE(pipe, i));
  1844	
  1845			blob_data[i].red = intel_color_lut_pack(REG_FIELD_GET(
  1846								LGC_PALETTE_RED_MASK, val), 8);
  1847			blob_data[i].green = intel_color_lut_pack(REG_FIELD_GET(
  1848								  LGC_PALETTE_GREEN_MASK, val), 8);
  1849			blob_data[i].blue = intel_color_lut_pack(REG_FIELD_GET(
  1850								 LGC_PALETTE_BLUE_MASK, val), 8);
  1851		}
  1852	
  1853		return blob;
  1854	}
  1855	

---
0-DAY CI Kernel Test Service, Intel Corporation
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