usbnet: Fix memory leak in usbnet_disconnect()

Currently usbnet_disconnect() unanchors and frees all deferred URBs
using usb_scuttle_anchored_urbs(), which does not free urb->context,
causing a memory leak as reported by syzbot.

Use a usb_get_from_anchor() while loop instead, similar to what we did
in commit 19cfe912c37b ("Bluetooth: btusb: Fix memory leak in
play_deferred").  Also free urb->sg.

Reported-and-tested-by: syzbot+dcd3e13cf4472f2e0ba1@syzkaller.appspotmail.com
Fixes: 69ee472f2706 ("usbnet & cdc-ether: Autosuspend for online devices")
Fixes: 638c5115a794 ("USBNET: support DMA SG")
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Link: https://lore.kernel.org/r/20220923042551.2745-1-yepeilin.cs@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index aaa89b4..e368b07 100644 (file)
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1598,6 +1598,7 @@ void usbnet_disconnect (struct usb_interface *intf)
        struct usbnet           *dev;
        struct usb_device       *xdev;
        struct net_device       *net;
+       struct urb              *urb;
 
        dev = usb_get_intfdata(intf);
        usb_set_intfdata(intf, NULL);
@@ -1614,7 +1615,11 @@ void usbnet_disconnect (struct usb_interface *intf)
        net = dev->net;
        unregister_netdev (net);
 
-       usb_scuttle_anchored_urbs(&dev->deferred);
+       while ((urb = usb_get_from_anchor(&dev->deferred))) {
+               dev_kfree_skb(urb->context);
+               kfree(urb->sg);
+               usb_free_urb(urb);
+       }
 
        if (dev->driver_info->unbind)
                dev->driver_info->unbind(dev, intf);