drm/edid: Fix a missing-check bug in drm_load_edid_firmware()

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@gmail.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190524023222.GA5302@zhanggen-UX430UQ

diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c
index 18d52dc4b21d1a0b5613e8f2e158cc0e6be78b07..2e8d043fc7e5166b221167f0d41f5da0c029e5bf 100644 (file)
--- a/drivers/gpu/drm/drm_edid_load.c
+++ b/drivers/gpu/drm/drm_edid_load.c
@@ -293,6 +293,8 @@ 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, ","))) {