* [PATCH] usbnet: smsc95xx: Fix use-after-free after removal
@ 2020-06-21 10:43 Tuomas Tynkkynen
2020-06-22 23:34 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Tuomas Tynkkynen @ 2020-06-21 10:43 UTC (permalink / raw)
To: steve.glendinning
Cc: UNGLinuxDriver, davem, kuba, netdev, linux-usb, linux-kernel,
Tuomas Tynkkynen
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is no longer active.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>
---
Compile tested only.
---
drivers/net/usb/smsc95xx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c
index 355be77f4241..3cf4dc3433f9 100644
--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -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;
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] usbnet: smsc95xx: Fix use-after-free after removal
2020-06-21 10:43 [PATCH] usbnet: smsc95xx: Fix use-after-free after removal Tuomas Tynkkynen
@ 2020-06-22 23:34 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2020-06-22 23:34 UTC (permalink / raw)
To: tuomas.tynkkynen
Cc: steve.glendinning, UNGLinuxDriver, kuba, netdev, linux-usb, linux-kernel
From: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Date: Sun, 21 Jun 2020 13:43:26 +0300
> 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>
Applied, thanks.
^ permalink raw reply [flat|nested] 2+ messages in thread
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