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From:   Niels Dossche <dossche.niels@gmail.com>
To:     linux-wireless@vger.kernel.org
Cc:     Amitkumar Karwar <amitkarwar@gmail.com>,
        Ganapathi Bhat <ganapathi017@gmail.com>,
        Sharvari Harisangam <sharvari.harisangam@nxp.com>,
        Xinming Hu <huxinming820@gmail.com>,
        Kalle Valo <kvalo@kernel.org>,
        Niels Dossche <dossche.niels@gmail.com>
Subject: [PATCH RFT] mwifiex: add mutex lock for call in mwifiex_dfs_chan_sw_work_queue
Date:   Sat, 19 Mar 2022 23:47:52 +0100
Message-Id: <20220319224751.72241-1-dossche.niels@gmail.com>
MIME-Version: 1.0
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Precedence: bulk

cfg80211_ch_switch_notify uses ASSERT_WDEV_LOCK to assert that
net_device->ieee80211_ptr->mtx is held during the function's execution.
mwifiex_dfs_chan_sw_work_queue is one of its callers, which does not
hold that lock, therefore violating the assertion.
Add a lock around the call.

Disclaimer:
I am currently working on a static analyser to detect missing locks.
This was a reported case. I manually verified the report by looking
at the code, so that I do not send wrong information or patches.
After concluding that this seems to be a true positive, I created
this patch.
However, as I do not in fact have this particular hardware,
I was unable to test it.

Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
---
 drivers/net/wireless/marvell/mwifiex/11h.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/11h.c b/drivers/net/wireless/marvell/mwifiex/11h.c
index d2ee6469e67b..f2cba764024e 100644
--- a/drivers/net/wireless/marvell/mwifiex/11h.c
+++ b/drivers/net/wireless/marvell/mwifiex/11h.c
@@ -285,6 +285,7 @@ void mwifiex_dfs_chan_sw_work_queue(struct work_struct *work)
 	struct mwifiex_private *priv =
 			container_of(delayed_work, struct mwifiex_private,
 				     dfs_chan_sw_work);
+	struct net_device *netdev;
 
 	bss_cfg = &priv->bss_cfg;
 	if (!bss_cfg->beacon_period) {
@@ -301,7 +302,11 @@ void mwifiex_dfs_chan_sw_work_queue(struct work_struct *work)
 		return;
 	}
 
+	netdev = priv->netdev;
+
 	mwifiex_dbg(priv->adapter, MSG,
 		    "indicating channel switch completion to kernel\n");
-	cfg80211_ch_switch_notify(priv->netdev, &priv->dfs_chandef);
+	mutex_lock(&netdev->ieee80211_ptr->mtx);
+	cfg80211_ch_switch_notify(netdev, &priv->dfs_chandef);
+	mutex_unlock(&netdev->ieee80211_ptr->mtx);
 }
-- 
2.35.1