spi: atmel-quadspi: Fix use-after-free on unbind

atmel_qspi_remove() accesses the driver's private data after calling
spi_unregister_controller() even though that function releases the last
reference on the spi_controller and thereby frees the private data.

Fix by switching over to the new devm_spi_alloc_master() helper which
keeps the private data accessible until the driver has unbound.

Fixes: 2d30ac5ed633 ("mtd: spi-nor: atmel-quadspi: Use spi-mem interface for atmel-quadspi driver")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v5.0+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v5.0+
Cc: Piotr Bugalski <bugalski.piotr@gmail.com>
Link: https://lore.kernel.org/r/4b05c65cf6f1ea3251484fe9a00b4c65478a1ae3.1607286887.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/atmel-quadspi.c b/drivers/spi/atmel-quadspi.c
index b44521d..1742ccc 100644 (file)
--- a/drivers/spi/atmel-quadspi.c
+++ b/drivers/spi/atmel-quadspi.c
@@ -535,7 +535,7 @@ static int atmel_qspi_probe(struct platform_device *pdev)
        struct resource *res;
        int irq, err = 0;
 
-       ctrl = spi_alloc_master(&pdev->dev, sizeof(*aq));
+       ctrl = devm_spi_alloc_master(&pdev->dev, sizeof(*aq));
        if (!ctrl)
                return -ENOMEM;
 
@@ -557,8 +557,7 @@ static int atmel_qspi_probe(struct platform_device *pdev)
        aq->regs = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(aq->regs)) {
                dev_err(&pdev->dev, "missing registers\n");
-               err = PTR_ERR(aq->regs);
-               goto exit;
+               return PTR_ERR(aq->regs);
        }
 
        /* Map the AHB memory */
@@ -566,8 +565,7 @@ static int atmel_qspi_probe(struct platform_device *pdev)
        aq->mem = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(aq->mem)) {
                dev_err(&pdev->dev, "missing AHB memory\n");
-               err = PTR_ERR(aq->mem);
-               goto exit;
+               return PTR_ERR(aq->mem);
        }
 
        aq->mmap_size = resource_size(res);
@@ -579,15 +577,14 @@ static int atmel_qspi_probe(struct platform_device *pdev)
 
        if (IS_ERR(aq->pclk)) {
                dev_err(&pdev->dev, "missing peripheral clock\n");
-               err = PTR_ERR(aq->pclk);
-               goto exit;
+               return PTR_ERR(aq->pclk);
        }
 
        /* Enable the peripheral clock */
        err = clk_prepare_enable(aq->pclk);
        if (err) {
                dev_err(&pdev->dev, "failed to enable the peripheral clock\n");
-               goto exit;
+               return err;
        }
 
        aq->caps = of_device_get_match_data(&pdev->dev);
@@ -638,8 +635,6 @@ disable_qspick:
        clk_disable_unprepare(aq->qspick);
 disable_pclk:
        clk_disable_unprepare(aq->pclk);
-exit:
-       spi_controller_put(ctrl);
 
        return err;
 }