In psb_intel_lvds_get_modes(), the return value of drm_mode_duplicate() is
assigned to mode, which will lead to a possible NULL pointer dereference
on failure of drm_mode_duplicate(). Add a check to avoid npd.

Cc: stable@vger.kernel.org
Fixes: 89c78134cc54 ("gma500: Add Poulsbo support")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v2:
- modified the patch according to suggestions;
- added Fixes line;
- added Cc stable.
---
 drivers/gpu/drm/gma500/psb_intel_lvds.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/gma500/psb_intel_lvds.c b/drivers/gpu/drm/gma500/psb_intel_lvds.c
index 8486de230ec9..8d1be94a443b 100644
--- a/drivers/gpu/drm/gma500/psb_intel_lvds.c
+++ b/drivers/gpu/drm/gma500/psb_intel_lvds.c
@@ -504,6 +504,9 @@ static int psb_intel_lvds_get_modes(struct drm_connector *connector)
 	if (mode_dev->panel_fixed_mode != NULL) {
 		struct drm_display_mode *mode =
 		    drm_mode_duplicate(dev, mode_dev->panel_fixed_mode);
+		if (!mode)
+			return 0;
+
 		drm_mode_probed_add(connector, mode);
 		return 1;
 	}
-- 
2.25.1

> In psb_intel_lvds_get_modes(), the return value of drm_mode_duplicate() is
> assigned to mode, which will lead to a possible NULL pointer dereference
> on failure of drm_mode_duplicate(). Add a check to avoid npd.

A) Can a wording approach (like the following) be a better change description?

   A null pointer is stored in the local variable “mode” after a call
   of the function “drm_mode_duplicate” failed. This pointer was passed to
   a subsequent call of the function “drm_mode_probed_add” where an undesirable
   dereference will be performed then.
   Thus add a corresponding return value check.


B) How do you think about to append parentheses to the function name
   in the summary phrase?


C) How do you think about to put similar results from static source code
   analyses into corresponding patch series?


Regards,
Markus