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Commit f01d35a1 authored by Al Viro's avatar Al Viro
Browse files

gadgetfs: use-after-free in ->aio_read() 



AIO_PREAD requests call ->aio_read() with iovec on caller's stack, so if
we are going to access it asynchronously, we'd better get ourselves
a copy - the one on kernel stack of aio_run_iocb() won't be there
anymore.  function/f_fs.c take care of doing that, legacy/inode.c
doesn't...

Cc: stable@vger.kernel.org
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 70e60d91

drivers/usb/gadget/legacy/inode.c

+12 −3
Original line number Diff line number Diff line
@@ -566,7 +566,6 @@ static ssize_t ep_copy_to_user(struct kiocb_priv *priv) 
		if (total == 0)

			break;

	}



	return len;

}
@@ -585,6 +584,7 @@ static void ep_user_copy_worker(struct work_struct *work) 
	aio_complete(iocb, ret, ret);



	kfree(priv->buf);

	kfree(priv->iv);

	kfree(priv);

}
@@ -605,6 +605,7 @@ static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req) 
	 */

	if (priv->iv == NULL || unlikely(req->actual == 0)) {

		kfree(req->buf);

		kfree(priv->iv);

		kfree(priv);

		iocb->private = NULL;

		/* aio_complete() reports bytes-transferred _and_ faults */
@@ -640,7 +641,7 @@ ep_aio_rwtail( 
	struct usb_request	*req;

	ssize_t			value;



	priv = kmalloc(sizeof *priv, GFP_KERNEL);

	priv = kzalloc(sizeof *priv, GFP_KERNEL);

	if (!priv) {

		value = -ENOMEM;

fail:
@@ -649,7 +650,14 @@ ep_aio_rwtail( 
	}

	iocb->private = priv;

	priv->iocb = iocb;

	priv->iv = iv;

	if (iv) {

		priv->iv = kmemdup(iv, nr_segs * sizeof(struct iovec),

				   GFP_KERNEL);

		if (!priv->iv) {

			kfree(priv);

			goto fail;

		}

	}

	priv->nr_segs = nr_segs;

	INIT_WORK(&priv->work, ep_user_copy_worker);
@@ -689,6 +697,7 @@ ep_aio_rwtail( 
	mutex_unlock(&epdata->lock);



	if (unlikely(value)) {

		kfree(priv->iv);

		kfree(priv);

		put_ep(epdata);

	} else