[PATCH] spi: lpspi: Fix use-after-free on unbind

[Lukas Wunner <lukas@xxxxxxxxx>]

Normally the last reference on an spi_controller is released by
spi_unregister_controller().  In the case of the i.MX lpspi driver,
the spi_controller is registered with devm_spi_register_controller(),
so spi_unregister_controller() is invoked automatically after the driver
has unbound.

However the driver already releases the last reference in
fsl_lpspi_remove() through a gratuitous call to spi_master_put(),
causing a use-after-free when spi_unregister_controller() is
subsequently invoked by the devres framework.

Fix by dropping the superfluous spi_master_put().

Fixes: 944c01a889d9 ("spi: lpspi: enable runtime pm for lpspi")
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v5.2+
Cc: Han Xu <han.xu@xxxxxxx>
---
 drivers/spi/spi-fsl-lpspi.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index 986b9793fd3c..a2886ee44e4c 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -938,9 +938,6 @@ static int fsl_lpspi_remove(struct platform_device *pdev)
 				spi_controller_get_devdata(controller);
 
 	pm_runtime_disable(fsl_lpspi->dev);
-
-	spi_master_put(controller);
-
 	return 0;
 }
 
-- 
2.28.0