[PATCH] wifi: mwifiex: fix use-after-free in mwifiex_adapter_cleanup()

[PATCH] wifi: mwifiex: fix use-after-free in mwifiex_adapter_cleanup()

[Daniel Hodges]

The mwifiex_adapter_cleanup() function uses timer_delete()
(non-synchronous) for the wakeup_timer before the adapter structure is
freed. This is incorrect because timer_delete() does not wait for any
running timer callback to complete.

If the wakeup_timer callback (wakeup_timer_fn) is executing when
mwifiex_adapter_cleanup() is called, the callback will continue to
access adapter fields (adapter->hw_status, adapter->if_ops.card_reset,
etc.) which may be freed by mwifiex_free_adapter() called later in the
mwifiex_remove_card() path.

Use timer_delete_sync() instead to ensure any running timer callback has
completed before returning.

Fixes: 4636187da60b ("mwifiex: add wakeup timer based recovery mechanism")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Hodges <git@danielhodges.dev>
---
 drivers/net/wireless/marvell/mwifiex/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/init.c b/drivers/net/wireless/marvell/mwifiex/init.c
index 4820010a86f6..5902e2c821f2 100644
--- a/drivers/net/wireless/marvell/mwifiex/init.c
+++ b/drivers/net/wireless/marvell/mwifiex/init.c
@@ -391,7 +391,7 @@ static void mwifiex_invalidate_lists(struct mwifiex_adapter *adapter)
 static void
 mwifiex_adapter_cleanup(struct mwifiex_adapter *adapter)
 {
-	timer_delete(&adapter->wakeup_timer);
+	timer_delete_sync(&adapter->wakeup_timer);
 	cancel_delayed_work_sync(&adapter->devdump_work);
 	mwifiex_cancel_all_pending_cmd(adapter);
 	wake_up_interruptible(&adapter->cmd_wait_q.wait);
-- 
2.52.0