spi: imx: fix use-after-free on unbind

commit 1c78c20 upstream.

The SPI subsystem frees the controller and any subsystem allocated
driver data as part of deregistration (unless the allocation is device
managed).

Take another reference before deregistering the controller so that the
driver data is not freed until the driver is done with it.

Fixes: 307c897 ("spi: spi-imx: replace struct spi_imx_data::bitbang by pointer to struct spi_controller")
Cc: stable@vger.kernel.org	# 5.19
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20260324082326.901043-2-johan@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jhovold

drivers/spi/spi-imx.c

@@ -1898,6 +1898,8 @@ static void spi_imx_remove(struct platform_device *pdev)
 	struct spi_imx_data *spi_imx = spi_controller_get_devdata(controller);
 	int ret;
 
+	spi_controller_get(controller);
+
 	spi_unregister_controller(controller);
 
 	ret = pm_runtime_get_sync(spi_imx->dev);
@@ -1911,6 +1913,8 @@ static void spi_imx_remove(struct platform_device *pdev)
 	pm_runtime_disable(spi_imx->dev);
 
 	spi_imx_sdma_exit(spi_imx);
+
+	spi_controller_put(controller);
 }
 
 static int __maybe_unused spi_imx_runtime_resume(struct device *dev)