[v1,08/13] drm/edid: add drm_edid_raw() to access the raw EDID data

Commit Message

Jani Nikula May 24, 2022, 10:39 a.m. UTC

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 <[e-mail]>
---
 drivers/gpu/drm/drm_edid.c | 26 ++++++++++++++++++++++++++
 include/drm/drm_edid.h     |  1 +
 2 files changed, 27 insertions(+)

Patch

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 09328298aabf..6617ea70ae5c 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2333,6 +2333,32 @@  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 289b956d31ea..f74ec9f7439b 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -584,6 +584,7 @@  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);