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path: root/drivers/gpu/drm/drm_edid.c
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Diffstat (limited to 'drivers/gpu/drm/drm_edid.c')
-rw-r--r--drivers/gpu/drm/drm_edid.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 6325877c5fd6..ea9a79bc9583 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1834,11 +1834,20 @@ static void connector_bad_edid(struct drm_connector *connector,
 			       u8 *edid, int num_blocks)
 {
 	int i;
-	u8 num_of_ext = edid[0x7e];
+	u8 last_block;
+
+	/*
+	 * 0x7e in the EDID is the number of extension blocks. The EDID
+	 * is 1 (base block) + num_ext_blocks big. That means we can think
+	 * of 0x7e in the EDID of the _index_ of the last block in the
+	 * combined chunk of memory.
+	 */
+	last_block = edid[0x7e];
 
 	/* Calculate real checksum for the last edid extension block data */
-	connector->real_edid_checksum =
-		drm_edid_block_checksum(edid + num_of_ext * EDID_LENGTH);
+	if (last_block < num_blocks)
+		connector->real_edid_checksum =
+			drm_edid_block_checksum(edid + last_block * EDID_LENGTH);
 
 	if (connector->bad_edid_counter++ && !drm_debug_enabled(DRM_UT_KMS))
 		return;