spi: spi-axi: fix potential use-after-free after deregistration

[ Upstream commit 4d5e0689dc9d5640ad46cdfbe1896b74d8df1661 ]

Take an extra reference to the controller before deregistering it to
prevent use-after-free in the interrupt handler in case an interrupt
fires before the line is disabled.

Fixes: b1353d1c1d45 ("spi: Add Analog Devices AXI SPI Engine controller support")
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c
index 6ab4c770022882eacc338a31b345c0d80bc1b541..68cfc351b47f6e10848cb176c7022307badf2509 100644 (file)
--- a/drivers/spi/spi-axi-spi-engine.c
+++ b/drivers/spi/spi-axi-spi-engine.c
@@ -553,7 +553,7 @@ err_put_master:
 
 static int spi_engine_remove(struct platform_device *pdev)
 {
-       struct spi_master *master = platform_get_drvdata(pdev);
+       struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
        struct spi_engine *spi_engine = spi_master_get_devdata(master);
        int irq = platform_get_irq(pdev, 0);
 
@@ -561,6 +561,8 @@ static int spi_engine_remove(struct platform_device *pdev)
 
        free_irq(irq, master);
 
+       spi_master_put(master);
+
        writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
        writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
        writel_relaxed(0x01, spi_engine->base + SPI_ENGINE_REG_RESET);