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    Subject[PATCH 4.14 33/88] net: usb: fix possible use-after-free in smsc75xx_bind
    Date
    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 62f2862c9775..8b9fd4e071f3 100644
    --- a/drivers/net/usb/smsc75xx.c
    +++ b/drivers/net/usb/smsc75xx.c
    @@ -1495,7 +1495,7 @@ 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);
    @@ -1504,7 +1504,7 @@ 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;
    @@ -1515,8 +1515,11 @@ static int smsc75xx_bind(struct usbnet *dev, struct usb_interface *intf)
    dev->net->max_mtu = MAX_SINGLE_PACKET_SIZE;
    return 0;

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

    @@ -1527,7 +1530,6 @@ 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
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