diff mbox

[05/11] mwifiex: don't drop lock between list-retrieval / list-deletion

Message ID 20170512164208.38725-5-briannorris@chromium.org (mailing list archive)
State Accepted
Commit 0f13acf0c61234b22e2c1478a932a7610b7ad7ca
Delegated to: Kalle Valo
Headers show

Commit Message

Brian Norris May 12, 2017, 4:42 p.m. UTC
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>
---
 drivers/net/wireless/marvell/mwifiex/cmdevt.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
diff mbox

Patch

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);