[PATCH 3.16 193/254] USB: UDC core: fix double-free in usb_add_gadget_udc_release

Ben Hutchings
2018-02-28T15:53:37Z

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;
}