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    Subject[PATCH 3.16 193/254] USB: UDC core: fix double-free in usb_add_gadget_udc_release
    3.16.55-rc1 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>
    [bwh: Backported to 3.16:
    - The err5 path is not presnet
    - Adjust filename]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    --- a/drivers/usb/gadget/udc-core.c
    +++ b/drivers/usb/gadget/udc-core.c
    @@ -219,11 +219,7 @@ 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;
    @@ -232,7 +228,11 @@ 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;

    @@ -241,7 +241,7 @@ 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);

    @@ -249,18 +249,16 @@ int usb_add_gadget_udc_release(struct de

    return 0;

    -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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