The patch below does not apply to the 5.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e1483ac030fb4c57734289742f1c1d38dca61e22 Mon Sep 17 00:00:00 2001

From: Lukas Wunner lukas@wunner.de Date: Wed, 11 Nov 2020 20:07:20 +0100 Subject: [PATCH] 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.160512103... Signed-off-by: Mark Brown broonie@kernel.org

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 7104cf17b848..197485f2c2b2 100644 --- 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 @@ static int bcm2835_spi_probe(struct platform_device *pdev) bcm2835_dma_release(ctlr, bs); out_clk_disable: clk_disable_unprepare(bs->clk); -out_controller_put: - spi_controller_put(ctlr); return err; }