spi: bcm2835: Fix use-after-free on unbind

bcm2835_spi_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: f8043872e796 ("spi: add driver for BCM2835")
Reported-by: Sascha Hauer <s.hauer@pengutronix.de>
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v3.10+: 123456789abc: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v3.10+
Cc: Vladimir Oltean <olteanv@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/ad66e0a0ad96feb848814842ecf5b6a4539ef35c.1605121038.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 7104cf1..197485f 100644 (file)
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -1278,7 +1278,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
        struct bcm2835_spi *bs;
        int err;
 
-       ctlr = spi_alloc_master(&pdev->dev, ALIGN(sizeof(*bs),
+       ctlr = devm_spi_alloc_master(&pdev->dev, ALIGN(sizeof(*bs),
                                                  dma_get_cache_alignment()));
        if (!ctlr)
                return -ENOMEM;
@@ -1299,23 +1299,17 @@ static int bcm2835_spi_probe(struct platform_device *pdev)
        bs->ctlr = ctlr;
 
        bs->regs = devm_platform_ioremap_resource(pdev, 0);
-       if (IS_ERR(bs->regs)) {
-               err = PTR_ERR(bs->regs);
-               goto out_controller_put;
-       }
+       if (IS_ERR(bs->regs))
+               return PTR_ERR(bs->regs);
 
        bs->clk = devm_clk_get(&pdev->dev, NULL);
-       if (IS_ERR(bs->clk)) {
-               err = dev_err_probe(&pdev->dev, PTR_ERR(bs->clk),
-                                   "could not get clk\n");
-               goto out_controller_put;
-       }
+       if (IS_ERR(bs->clk))
+               return dev_err_probe(&pdev->dev, PTR_ERR(bs->clk),
+                                    "could not get clk\n");
 
        bs->irq = platform_get_irq(pdev, 0);
-       if (bs->irq <= 0) {
-               err = bs->irq ? bs->irq : -ENODEV;
-               goto out_controller_put;
-       }
+       if (bs->irq <= 0)
+               return bs->irq ? bs->irq : -ENODEV;
 
        clk_prepare_enable(bs->clk);
 
@@ -1349,8 +1343,6 @@ out_dma_release:
        bcm2835_dma_release(ctlr, bs);
 out_clk_disable:
        clk_disable_unprepare(bs->clk);
-out_controller_put:
-       spi_controller_put(ctlr);
        return err;
 }