drm/edid: add drm_edid_raw() to access the raw EDID data

Unfortunately, there are still plenty of interfaces around that require
a struct edid pointer, and it's impossible to change them all at
once. Add an accessor to the raw EDID data to help the transition.

While there are no such cases now, be defensive against raw EDID
extension count indicating bigger EDID than is actually allocated.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/fb55d0b580d556bf2b8e58070239657ac9cb4b2f.1656494768.git.jani.nikula@intel.com

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 41b3de52b8f1fe7aedf84c06b647757a382ed48f..1c761e12820ee0b965efdd5380694a70ce2ef0a7 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2359,6 +2359,32 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 }
 EXPORT_SYMBOL_GPL(drm_do_get_edid);
 
+/**
+ * drm_edid_raw - Get a pointer to the raw EDID data.
+ * @drm_edid: drm_edid container
+ *
+ * Get a pointer to the raw EDID data.
+ *
+ * This is for transition only. Avoid using this like the plague.
+ *
+ * Return: Pointer to raw EDID data.
+ */
+const struct edid *drm_edid_raw(const struct drm_edid *drm_edid)
+{
+       if (!drm_edid || !drm_edid->size)
+               return NULL;
+
+       /*
+        * Do not return pointers where relying on EDID extension count would
+        * lead to buffer overflow.
+        */
+       if (WARN_ON(edid_size(drm_edid->edid) > drm_edid->size))
+               return NULL;
+
+       return drm_edid->edid;
+}
+EXPORT_SYMBOL(drm_edid_raw);
+
 /* Allocate struct drm_edid container *without* duplicating the edid data */
 static const struct drm_edid *_drm_edid_alloc(const void *edid, size_t size)
 {

diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index aeb2fa95bc047ea4ed3189a7a32abbb91a993815..2181977ae6839c6caedb0957c43306dcf4e8da35 100644 (file)
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -597,6 +597,7 @@ drm_display_mode_from_cea_vic(struct drm_device *dev,
 const struct drm_edid *drm_edid_alloc(const void *edid, size_t size);
 const struct drm_edid *drm_edid_dup(const struct drm_edid *drm_edid);
 void drm_edid_free(const struct drm_edid *drm_edid);
+const struct edid *drm_edid_raw(const struct drm_edid *drm_edid);
 const struct drm_edid *drm_edid_read(struct drm_connector *connector);
 const struct drm_edid *drm_edid_read_ddc(struct drm_connector *connector,
                                         struct i2c_adapter *adapter);