[PATCH 4.5 40/87] mei: fix NULL dereferencing during FW initiated disconnection

Greg Kroah-Hartman
2016-05-30T21:50:38Z

From: Alexander Usyskin <alexander.usyskin@intel.com>

commit 6a8d648c8d1824117a9e9edb948ed1611fb013c0 upstream.

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.

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>

---
drivers/misc/mei/client.c | 4 ++++
drivers/misc/mei/hbm.c | 3 +--
drivers/misc/mei/interrupt.c | 5 +----
3 files changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/misc/mei/client.c
+++ b/drivers/misc/mei/client.c
@@ -1735,6 +1735,10 @@ void mei_cl_complete(struct mei_cl *cl,
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);
}
--- a/drivers/misc/mei/hbm.c
+++ b/drivers/misc/mei/hbm.c
@@ -873,8 +873,7 @@ static int mei_hbm_fw_disconnect_req(str
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;
}
--- a/drivers/misc/mei/interrupt.c
+++ b/drivers/misc/mei/interrupt.c
@@ -184,10 +184,7 @@ static int mei_cl_irq_disconnect_rsp(str
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;
}