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From:   Dongliang Mu <mudongliangabcd@gmail.com>
To:     steve.glendinning@shawell.net, davem@davemloft.net,
        kuba@kernel.org, paskripkin@gmail.com
Cc:     netdev@vger.kernel.org, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Dongliang Mu <mudongliangabcd@gmail.com>
Subject: [PATCH] net: usb: fix possible use-after-free in smsc75xx_bind
Date:   Mon, 14 Jun 2021 23:37:12 +0800
Message-Id: <20210614153712.2172662-1-mudongliangabcd@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The commit 46a8b29c6306 ("net: usb: fix memory leak in smsc75xx_bind")
fails to clean up the work scheduled in smsc75xx_reset->
smsc75xx_set_multicast, which leads to use-after-free if the work is
scheduled to start after the deallocation. In addition, this patch also
removes one dangling pointer - dev->data[0].

This patch calls cancel_work_sync to cancel the schedule work and set
the dangling pointer to NULL.

Fixes: 46a8b29c6306 ("net: usb: fix memory leak in smsc75xx_bind")
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
---
 drivers/net/usb/smsc75xx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/usb/smsc75xx.c b/drivers/net/usb/smsc75xx.c
index b286993da67c..f81740fcc8d5 100644
--- a/drivers/net/usb/smsc75xx.c
+++ b/drivers/net/usb/smsc75xx.c
@@ -1504,7 +1504,10 @@ static int smsc75xx_bind(struct usbnet *dev, struct usb_interface *intf)
 	return 0;
 
 err:
+	cancel_work_sync(&pdata->set_multicast);
 	kfree(pdata);
+	pdata = NULL;
+	dev->data[0] = 0;
 	return ret;
 }
 
-- 
2.25.1