From: Alexander Usyskin <alexander.usyskin@intel.com>
Date: Sun, 17 Apr 2016 16:16:03 +0000 (-0400)
Subject: mei: fix NULL dereferencing during FW initiated disconnection
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6a8d648c8d1824117a9e9edb948ed1611fb013c0;p=linux-beck.git

mei: fix NULL dereferencing during FW initiated disconnection

In the case when disconnection is initiated from the FW
the driver is flushing items from the write control list while
iterating over it:

mei_irq_write_handler()
    list_for_each_entry_safe(ctrl_wr_list)         <-- outer loop
         mei_cl_irq_disconnect_rsp()
             mei_cl_set_disconnected()
                 mei_io_list_flush(ctrl_wr_list)   <-- destorying list

We move the list flushing to the completion routine.

Cc: <stable@vger.kernel.org> #4.2+
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/misc/mei/client.c b/drivers/misc/mei/client.c
index bab17e4197b6..09f5280fa021 100644
--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -1766,6 +1766,10 @@ void mei_cl_complete(struct mei_cl *cl, struct mei_cl_cb *cb)
 		if (waitqueue_active(&cl->wait))
 			wake_up(&cl->wait);
 
+		break;
+	case MEI_FOP_DISCONNECT_RSP:
+		mei_io_cb_free(cb);
+		mei_cl_set_disconnected(cl);
 		break;
 	default:
 		BUG_ON(0);
diff --git a/drivers/misc/mei/hbm.c b/drivers/misc/mei/hbm.c
index 5eaa4638e824..5aa606c8a827 100644
--- a/drivers/misc/mei/hbm.c
+++ b/drivers/misc/mei/hbm.c
@@ -877,8 +877,7 @@ static int mei_hbm_fw_disconnect_req(struct mei_device *dev,
 		cb = mei_io_cb_init(cl, MEI_FOP_DISCONNECT_RSP, NULL);
 		if (!cb)
 			return -ENOMEM;
-		cl_dbg(dev, cl, "add disconnect response as first\n");
-		list_add(&cb->list, &dev->ctrl_wr_list.list);
+		list_add_tail(&cb->list, &dev->ctrl_wr_list.list);
 	}
 	return 0;
 }
diff --git a/drivers/misc/mei/interrupt.c b/drivers/misc/mei/interrupt.c
index 1e5cb1f704f8..704dc6caad6d 100644
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -194,10 +194,7 @@ static int mei_cl_irq_disconnect_rsp(struct mei_cl *cl, struct mei_cl_cb *cb,
 		return -EMSGSIZE;
 
 	ret = mei_hbm_cl_disconnect_rsp(dev, cl);
-	mei_cl_set_disconnected(cl);
-	mei_io_cb_free(cb);
-	mei_me_cl_put(cl->me_cl);
-	cl->me_cl = NULL;
+	list_move_tail(&cb->list, &cmpl_list->list);
 
 	return ret;
 }