From 0f13acf0c61234b22e2c1478a932a7610b7ad7ca Mon Sep 17 00:00:00 2001
From: Brian Norris <briannorris@chromium.org>
Date: Fri, 12 May 2017 09:42:02 -0700
Subject: [PATCH] mwifiex: don't drop lock between list-retrieval / list-deletion
Git-commit: 0f13acf0c61234b22e2c1478a932a7610b7ad7ca
Patch-mainline: v4.13-rc1
References: FATE#326294

mwifiex_exec_next_cmd() seems to have a classic TOCTOU race, where we
drop the list lock in between retrieving the next command and deleting
it from the list. This potentially leaves room for someone else to also
retrieve / steal this node from the list (e.g.,
mwifiex_cancel_all_pending_cmd()).

Let's keep holding the lock while we do our 'ps_state' sanity checks.
There should be no harm in continuing to hold this lock for a bit more.

Noticed only by code inspection.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/marvell/mwifiex/cmdevt.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/cmdevt.c b/drivers/net/wireless/marvell/mwifiex/cmdevt.c
index 5fd6c53d7b06..95221306a4e5 100644
--- a/drivers/net/wireless/marvell/mwifiex/cmdevt.c
+++ b/drivers/net/wireless/marvell/mwifiex/cmdevt.c
@@ -761,8 +761,6 @@ int mwifiex_exec_next_cmd(struct mwifiex_adapter *adapter)
 	}
 	cmd_node = list_first_entry(&adapter->cmd_pending_q,
 				    struct cmd_ctrl_node, list);
-	spin_unlock_irqrestore(&adapter->cmd_pending_q_lock,
-			       cmd_pending_q_flags);
 
 	host_cmd = (struct host_cmd_ds_command *) (cmd_node->cmd_skb->data);
 	priv = cmd_node->priv;
@@ -771,11 +769,12 @@ int mwifiex_exec_next_cmd(struct mwifiex_adapter *adapter)
 		mwifiex_dbg(adapter, ERROR,
 			    "%s: cannot send cmd in sleep state,\t"
 			    "this should not happen\n", __func__);
+		spin_unlock_irqrestore(&adapter->cmd_pending_q_lock,
+				       cmd_pending_q_flags);
 		spin_unlock_irqrestore(&adapter->mwifiex_cmd_lock, cmd_flags);
 		return ret;
 	}
 
-	spin_lock_irqsave(&adapter->cmd_pending_q_lock, cmd_pending_q_flags);
 	list_del(&cmd_node->list);
 	spin_unlock_irqrestore(&adapter->cmd_pending_q_lock,
 			       cmd_pending_q_flags);
-- 
2.19.2