[PATCH] drm_edid-load: Fix a missing-check bug in drm_load_edid_firmware()

[Gen Zhang]

In drm_load_edid_firmware(), fwstr is allocated by kstrdup(). And fwstr
is dereferenced in the following codes. However, memory allocation 
functions such as kstrdup() may fail and returns NULL. Dereferencing 
this null pointer may cause the kernel go wrong. Thus we should check 
this kstrdup() operation.
Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to
the caller site.

Signed-off-by: Gen Zhang <blackgod016574 at gmail.com>
Reviewed-by: Jani Nikula <jani.nikula at intel.com>
---
diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c
index a491509..a0e107a 100644
--- a/drivers/gpu/drm/drm_edid_load.c
+++ b/drivers/gpu/drm/drm_edid_load.c
@@ -290,6 +290,8 @@ struct edid *drm_load_edid_firmware(struct drm_connector *connector)
 	 * the last one found one as a fallback.
 	 */
 	fwstr = kstrdup(edid_firmware, GFP_KERNEL);
+	if (!fwstr)
+		return ERR_PTR(-ENOMEM);
 	edidstr = fwstr;
 
 	while ((edidname = strsep(&edidstr, ","))) {
---