drm/edid: fix info leak when failing to get panel id

Make sure to clear the transfer buffer before fetching the EDID to
avoid leaking slab data to the logs on errors that leave the buffer
unchanged.

Fixes: 69c7717 ("drm/edid: Dump the EDID when drm_edid_get_panel_id() has an error")
Cc: [email protected]	# 6.2
Cc: Douglas Anderson <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>
Reviewed-by: Jani Nikula <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Signed-off-by: Douglas Anderson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: jhovold

drivers/gpu/drm/drm_edid.c

@@ -2797,7 +2797,7 @@ u32 drm_edid_get_panel_id(struct i2c_adapter *adapter)
 	 * the EDID then we'll just return 0.
 	 */
 
-	base_block = kmalloc(EDID_LENGTH, GFP_KERNEL);
+	base_block = kzalloc(EDID_LENGTH, GFP_KERNEL);
 	if (!base_block)
 		return 0;