netdev - [PATCH] cfg80211: fix double-free after changing network namespace

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Message-Id: <20191126100543.782023-1-stefan.buehler@tik.uni-stuttgart.de>
Date:   Tue, 26 Nov 2019 11:05:44 +0100
From:   "Stefan Bühler" 
        <stefan.buehler@....uni-stuttgart.de>
To:     Johannes Berg <johannes@...solutions.net>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        Stefan Bühler <source@...uehler.de>
Subject: [PATCH] cfg80211: fix double-free after changing network namespace

From: Stefan Bühler <source@...uehler.de>

If wdev->wext.keys was initialized it didn't get reset to NULL on
unregister (and it doesn't get set in cfg80211_init_wdev either), but
wdev is reused if unregister was triggered through
cfg80211_switch_netns.

The next unregister (for whatever reason) will try to free
wdev->wext.keys again.

Signed-off-by: Stefan Bühler <source@...uehler.de>
---
 net/wireless/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 350513744575..3e25229a059d 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1102,6 +1102,7 @@ static void __cfg80211_unregister_wdev(struct wireless_dev *wdev, bool sync)
 
 #ifdef CONFIG_CFG80211_WEXT
 	kzfree(wdev->wext.keys);
+	wdev->wext.keys = NULL;
 #endif
 	/* only initialized if we have a netdev */
 	if (wdev->netdev)
-- 
2.24.0