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    Subject[PATCH 4.14 079/118] USB: UDC core: fix double-free in usb_add_gadget_udc_release
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Alan Stern <stern@rowland.harvard.edu>

    commit 7ae2c3c280db183ca9ada2675c34ec2f7378abfa upstream.

    The error-handling pathways in usb_add_gadget_udc_release() are messed
    up. Aside from the uninformative statement labels, they can deallocate
    the udc structure after calling put_device(), which is a double-free.
    This was observed by KASAN in automatic testing.

    This patch cleans up the routine. It preserves the requirement that
    when any failure occurs, we call put_device(&gadget->dev).

    Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
    Reported-by: Fengguang Wu <fengguang.wu@intel.com>
    Reviewed-by: Peter Chen <peter.chen@nxp.com>
    Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/usb/gadget/udc/core.c | 28 +++++++++++++---------------
    1 file changed, 13 insertions(+), 15 deletions(-)

    --- a/drivers/usb/gadget/udc/core.c
    +++ b/drivers/usb/gadget/udc/core.c
    @@ -1158,11 +1158,7 @@ int usb_add_gadget_udc_release(struct de

    udc = kzalloc(sizeof(*udc), GFP_KERNEL);
    if (!udc)
    - goto err1;
    -
    - ret = device_add(&gadget->dev);
    - if (ret)
    - goto err2;
    + goto err_put_gadget;

    device_initialize(&udc->dev);
    udc->dev.release = usb_udc_release;
    @@ -1171,7 +1167,11 @@ int usb_add_gadget_udc_release(struct de
    udc->dev.parent = parent;
    ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
    if (ret)
    - goto err3;
    + goto err_put_udc;
    +
    + ret = device_add(&gadget->dev);
    + if (ret)
    + goto err_put_udc;

    udc->gadget = gadget;
    gadget->udc = udc;
    @@ -1181,7 +1181,7 @@ int usb_add_gadget_udc_release(struct de

    ret = device_add(&udc->dev);
    if (ret)
    - goto err4;
    + goto err_unlist_udc;

    usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
    udc->vbus = true;
    @@ -1189,27 +1189,25 @@ int usb_add_gadget_udc_release(struct de
    /* pick up one of pending gadget drivers */
    ret = check_pending_gadget_drivers(udc);
    if (ret)
    - goto err5;
    + goto err_del_udc;

    mutex_unlock(&udc_lock);

    return 0;

    -err5:
    + err_del_udc:
    device_del(&udc->dev);

    -err4:
    + err_unlist_udc:
    list_del(&udc->list);
    mutex_unlock(&udc_lock);

    -err3:
    - put_device(&udc->dev);
    device_del(&gadget->dev);

    -err2:
    - kfree(udc);
    + err_put_udc:
    + put_device(&udc->dev);

    -err1:
    + err_put_gadget:
    put_device(&gadget->dev);
    return ret;
    }

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