[PATCH 4.9 29/71] net: usb: fix possible use-after-free in smsc75xx_bind

Sasha Levin
2021-06-28T15:19:35Z

From: Dongliang Mu <mudongliangabcd@gmail.com>

[ Upstream commit 56b786d86694e079d8aad9b314e015cd4ac02a3d ]

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 a dangling pointer - dev->data[0].

This patch calls cancel_work_sync to cancel the scheduled 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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/usb/smsc75xx.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/usb/smsc75xx.c b/drivers/net/usb/smsc75xx.c
index 3a391ae5c4e0..841d97491592 100644
--- a/drivers/net/usb/smsc75xx.c
+++ b/drivers/net/usb/smsc75xx.c
@@ -1497,7 +1497,7 @@ static int smsc75xx_bind(struct usbnet *dev, struct usb_interface *intf)
ret = smsc75xx_wait_ready(dev, 0);
if (ret < 0) {
netdev_warn(dev->net, "device not ready in smsc75xx_bind\n");
- goto err;
+ goto free_pdata;
}

smsc75xx_init_mac_address(dev);
@@ -1506,7 +1506,7 @@ static int smsc75xx_bind(struct usbnet *dev, struct usb_interface *intf)
ret = smsc75xx_reset(dev);
if (ret < 0) {
netdev_warn(dev->net, "smsc75xx_reset error %d\n", ret);
- goto err;
+ goto cancel_work;
}

dev->net->netdev_ops = &smsc75xx_netdev_ops;
@@ -1516,8 +1516,11 @@ static int smsc75xx_bind(struct usbnet *dev, struct usb_interface *intf)
dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
return 0;

-err:
+cancel_work:
+ cancel_work_sync(&pdata->set_multicast);
+free_pdata:
kfree(pdata);
+ dev->data[0] = 0;
return ret;
}

@@ -1528,7 +1531,6 @@ static void smsc75xx_unbind(struct usbnet *dev, struct usb_interface *intf)
cancel_work_sync(&pdata->set_multicast);
netif_dbg(dev, ifdown, dev->net, "free pdata\n");
kfree(pdata);
- pdata = NULL;
dev->data[0] = 0;
}
}
--
2.30.2