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Commit 38740a5b authored by Lars-Peter Clausen's avatar Lars-Peter Clausen Committed by Felipe Balbi
Browse files

usb: gadget: f_fs: Fix use-after-free 



When using asynchronous read or write operations on the USB endpoints the
issuer of the IO request is notified by calling the ki_complete() callback
of the submitted kiocb when the URB has been completed.

Calling this ki_complete() callback will free kiocb. Make sure that the
structure is no longer accessed beyond that point, otherwise undefined
behaviour might occur.

Fixes: 2e4c7553 ("usb: gadget: f_fs: add aio support")
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarFelipe Balbi <felipe.balbi@linux.intel.com>
parent 9772b47a

drivers/usb/gadget/function/f_fs.c

+2 −3
Original line number Diff line number Diff line
@@ -646,6 +646,7 @@ static void ffs_user_copy_worker(struct work_struct *work) 
						   work);

	int ret = io_data->req->status ? io_data->req->status :

					 io_data->req->actual;

	bool kiocb_has_eventfd = io_data->kiocb->ki_flags & IOCB_EVENTFD;



	if (io_data->read && ret > 0) {

		use_mm(io_data->mm);
@@ -657,13 +658,11 @@ static void ffs_user_copy_worker(struct work_struct *work) 


	io_data->kiocb->ki_complete(io_data->kiocb, ret, ret);



	if (io_data->ffs->ffs_eventfd &&

	    !(io_data->kiocb->ki_flags & IOCB_EVENTFD))

	if (io_data->ffs->ffs_eventfd && !kiocb_has_eventfd)

		eventfd_signal(io_data->ffs->ffs_eventfd, 1);



	usb_ep_free_request(io_data->ep, io_data->req);



	io_data->kiocb->private = NULL;

	if (io_data->read)

		kfree(io_data->to_free);

	kfree(io_data->buf);