USB: usblp: fix use-after-free on disconnect

commit 7a759197974894213621aa65f0571b51904733d6 upstream.

A recent commit addressing a runtime PM use-count regression, introduced
a use-after-free by not making sure we held a reference to the struct
usb_interface for the lifetime of the driver data.

Fixes: 9a31535859bf ("USB: usblp: fix runtime PM after driver unbind")
Reported-by: syzbot+cd24df4d075c319ebfc5@syzkaller.appspotmail.com
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191015175522.18490-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
index 5e2afd6a0598d01ccc2cc57a83b5bc5181f5da56..1db3ab4b846eae0c5b1e21484b8a64446596c21d 100644 (file)
--- a/drivers/usb/class/usblp.c
+++ b/drivers/usb/class/usblp.c
@@ -447,6 +447,7 @@ static void usblp_cleanup(struct usblp *usblp)
        kfree(usblp->readbuf);
        kfree(usblp->device_id_string);
        kfree(usblp->statusbuf);
+       usb_put_intf(usblp->intf);
        kfree(usblp);
 }
 
@@ -1104,7 +1105,7 @@ static int usblp_probe(struct usb_interface *intf,
        init_waitqueue_head(&usblp->wwait);
        init_usb_anchor(&usblp->urbs);
        usblp->ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
-       usblp->intf = intf;
+       usblp->intf = usb_get_intf(intf);
 
        /* Malloc device ID string buffer to the largest expected length,
         * since we can re-query it on an ioctl and a dynamic string
@@ -1193,6 +1194,7 @@ abort:
        kfree(usblp->readbuf);
        kfree(usblp->statusbuf);
        kfree(usblp->device_id_string);
+       usb_put_intf(usblp->intf);
        kfree(usblp);
 abort_ret:
        return retval;