[PATCH 4.17 17/67] mei: discard messages from not connected client during power down.

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>

commit b7a020bff31318fc8785e6f96b1d38c1625cf1fb upstream.

This fixes regression introduced by
commit 8d52af6795c0 ("mei: speed up the power down flow")

In power down or suspend flow a message can still be received
from the FW because the clients fake disconnection.
In normal case we interpret messages w/o destination as corrupted
and link reset is performed in order to clean the channel,
but during power down link reset is already in progress resulting
in endless loop. To resolve the issue under power down flow we
discard messages silently.

Cc: <stable@xxxxxxxxxxxxxxx> 4.16+
Fixes: 8d52af6795c0 ("mei: speed up the power down flow")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199541
Signed-off-by: Alexander Usyskin <alexander.usyskin@xxxxxxxxx>
Signed-off-by: Tomas Winkler <tomas.winkler@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/misc/mei/interrupt.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -310,8 +310,11 @@ int mei_irq_read_handler(struct mei_devi
 	if (&cl->link == &dev->file_list) {
 		/* A message for not connected fixed address clients
 		 * should be silently discarded
+		 * On power down client may be force cleaned,
+		 * silently discard such messages
 		 */
-		if (hdr_is_fixed(mei_hdr)) {
+		if (hdr_is_fixed(mei_hdr) ||
+		    dev->dev_state == MEI_DEV_POWER_DOWN) {
 			mei_irq_discard_msg(dev, mei_hdr);
 			ret = 0;
 			goto reset_slots;