blob: 9929977a61c21ecca277c93712242c156a346031 [file] [log] [blame]
From 85110f90f47c6fd727735253b0b73929d5cb2d60 Mon Sep 17 00:00:00 2001
From: Tuomas Tynkkynen <>
Date: Sun, 21 Jun 2020 13:43:26 +0300
Subject: [PATCH] usbnet: smsc95xx: Fix use-after-free after removal
commit b835a71ef64a61383c414d6bf2896d2c0161deca upstream.
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is no longer active.
Signed-off-by: Tuomas Tynkkynen <>
Signed-off-by: David S. Miller <>
Signed-off-by: Paul Gortmaker <>
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");
pdata = NULL;