[PATCH] net: usb: fix possible use-after-free in smsc75xx_bind

Dongliang Mu
2021-06-14T15:38:39Z

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