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

[ Upstream commit 9f1f1a2dab38d4ce87a13565cf4dc1b73bef3a5f ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/drm_edid_load.c b/drivers/gpu/drm/drm_edid_load.c
index a4915099aaa99223b56de4181c26510303769966..a0e107abc40d722c7d5bf06c74c5c4bbb509dd68 100644 (file)
--- 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, ","))) {