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Commit 9aacd823 authored by Johan Hovold's avatar Johan Hovold Committed by Greg Kroah-Hartman
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spi: fix use-after-free at controller deregistration 



commit 67f7b278 upstream.

The controller is typically freed as part of device_unregister() so
store the bus id before deregistration to avoid use-after-free when the
id is later released.

Fixes: 9b61e302 ("spi: Pick spi bus number from Linux idr or spi alias")
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d3e36fd0

drivers/spi/spi.c

+3 −2
Original line number Diff line number Diff line
@@ -2245,11 +2245,12 @@ static int __unregister(struct device *dev, void *null) 
void spi_unregister_controller(struct spi_controller *ctlr)

{

	struct spi_controller *found;

	int id = ctlr->bus_num;

	int dummy;



	/* First make sure that this controller was ever added */

	mutex_lock(&board_lock);

	found = idr_find(&spi_master_idr, ctlr->bus_num);

	found = idr_find(&spi_master_idr, id);

	mutex_unlock(&board_lock);

	if (found != ctlr) {

		dev_dbg(&ctlr->dev,
@@ -2269,7 +2270,7 @@ void spi_unregister_controller(struct spi_controller *ctlr) 
	device_unregister(&ctlr->dev);

	/* free bus id */

	mutex_lock(&board_lock);

	idr_remove(&spi_master_idr, ctlr->bus_num);

	idr_remove(&spi_master_idr, id);

	mutex_unlock(&board_lock);

}

EXPORT_SYMBOL_GPL(spi_unregister_controller);