[PATCH for v4.8] cec-edid: check for IEEE identifier

[Hans Verkuil]

The cec_get_edid_spa_location() function did not verify that the IEEE
identifier in the Vendor Specific Data Block matched the HDMI-LLC
identifier. This could result in the wrong VSDB block being returned.

For example, for HDMI 2.0 EDIDs there is also a HDMI Forum VSDB.

So check the IEEE identifier as well.

Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
---
diff --git a/drivers/media/cec-edid.c b/drivers/media/cec-edid.c
index 7001824..5719b99 100644
--- a/drivers/media/cec-edid.c
+++ b/drivers/media/cec-edid.c
@@ -70,7 +70,10 @@ static unsigned int cec_get_edid_spa_location(const u8 *edid, unsigned int size)
 				u8 tag = edid[i] >> 5;
 				u8 len = edid[i] & 0x1f;

-				if (tag == 3 && len >= 5 && i + len <= end)
+				if (tag == 3 && len >= 5 && i + len <= end &&
+				    edid[i + 1] == 0x03 &&
+				    edid[i + 2] == 0x0c &&
+				    edid[i + 3] == 0x00)
 					return i + 4;
 				i += len + 1;
 			} while (i < end);