From: Lukas Wunner <lukas@wunner.de>
Date: Thu, 10 Dec 2020 19:20:01 +0000 (+0100)
Subject: spi: bcm2835aux: Fix use-after-free on unbind
X-Git-Tag: v4.4.249~130
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=31f2b92445e984729e0567e5d1a249a467e7a8db;p=thirdparty%2Fkernel%2Fstable.git

spi: bcm2835aux: Fix use-after-free on unbind

[ Upstream commit e13ee6cc4781edaf8c7321bee19217e3702ed481 ]

bcm2835aux_spi_remove() accesses the driver's private data after calling
spi_unregister_master() even though that function releases the last
reference on the spi_master 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: b9dd3f6d4172 ("spi: bcm2835aux: Fix controller unregister order")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v4.4+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v4.4+: b9dd3f6d4172: spi: bcm2835aux: Fix controller unregister order
Cc: <stable@vger.kernel.org> # v4.4+
Link: https://lore.kernel.org/r/b290b06357d0c0bdee9cecc539b840a90630f101.1605121038.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
index 5ffc2765a8ddf..79edab7b384ce 100644
--- a/drivers/spi/spi-bcm2835aux.c
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -381,7 +381,7 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)
 	unsigned long clk_hz;
 	int err;
 
-	master = spi_alloc_master(&pdev->dev, sizeof(*bs));
+	master = devm_spi_alloc_master(&pdev->dev, sizeof(*bs));
 	if (!master) {
 		dev_err(&pdev->dev, "spi_alloc_master() failed\n");
 		return -ENOMEM;
@@ -411,30 +411,26 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)
 	/* the main area */
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	bs->regs = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(bs->regs)) {
-		err = PTR_ERR(bs->regs);
-		goto out_master_put;
-	}
+	if (IS_ERR(bs->regs))
+		return PTR_ERR(bs->regs);
 
 	bs->clk = devm_clk_get(&pdev->dev, NULL);
 	if ((!bs->clk) || (IS_ERR(bs->clk))) {
-		err = PTR_ERR(bs->clk);
 		dev_err(&pdev->dev, "could not get clk: %d\n", err);
-		goto out_master_put;
+		return PTR_ERR(bs->clk);
 	}
 
 	bs->irq = platform_get_irq(pdev, 0);
 	if (bs->irq <= 0) {
 		dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
-		err = bs->irq ? bs->irq : -ENODEV;
-		goto out_master_put;
+		return bs->irq ? bs->irq : -ENODEV;
 	}
 
 	/* this also enables the HW block */
 	err = clk_prepare_enable(bs->clk);
 	if (err) {
 		dev_err(&pdev->dev, "could not prepare clock: %d\n", err);
-		goto out_master_put;
+		return err;
 	}
 
 	/* just checking if the clock returns a sane value */
@@ -467,8 +463,6 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)
 
 out_clk_disable:
 	clk_disable_unprepare(bs->clk);
-out_master_put:
-	spi_master_put(master);
 	return err;
 }