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: 2e4c7553cd6f ("usb: gadget: f_fs: add aio support")
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index e21ca2bd..15b648c 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -646,6 +646,7 @@
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 @@
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);