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usbnet: smsc95xx: Fix use-after-free after removal 

Syzbot reports an use-after-free in workqueue context:

BUG: KASAN: use-after-free in mutex_unlock+0x19/0x40 kernel/locking/mutex.c:737
 mutex_unlock+0x19/0x40 kernel/locking/mutex.c:737
 __smsc95xx_mdio_read drivers/net/usb/smsc95xx.c:217 [inline]
 smsc95xx_mdio_read+0x583/0x870 drivers/net/usb/smsc95xx.c:278
 check_carrier+0xd1/0x2e0 drivers/net/usb/smsc95xx.c:644
 process_one_work+0x777/0xf90 kernel/workqueue.c:2274
 worker_thread+0xa8f/0x1430 kernel/workqueue.c:2420
 kthread+0x2df/0x300 kernel/kthread.c:255

It looks like that smsc95xx_unbind() is freeing the structures that are
still in use by the concurrently running workqueue callback. Thus switch
to using cancel_delayed_work_sync() to ensure the work callback really
is no longer active.

Reported-by: syzbot+29dc7d4ae19b703ff947@syzkaller.appspotmail.com
Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tuomas Tynkkynen 2020-06-21 13:43:26 +03:00 committed by David S. Miller
parent f3fe412b0a
commit b835a71ef6
1 changed files with 1 additions and 1 deletions
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2
drivers/net/usb/smsc95xx.c
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@ -1324,7 +1324,7 @@ static void smsc95xx_unbind(struct usbnet *dev, struct usb_interface *intf)
struct smsc95xx_priv *pdata = (struct smsc95xx_priv *)(dev->data[0]);
if (pdata) {
cancel_delayed_work(&pdata->carrier_check);
cancel_delayed_work_sync(&pdata->carrier_check);
netif_dbg(dev, ifdown, dev->net, "free pdata\n");
kfree(pdata);
pdata = NULL;