linux-kernel - [PATCH] spi: fsl-dspi: use devm_spi_alloc

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Date:   Wed, 10 Nov 2021 17:17:54 +0100
From:   Michael Walle <michael@...le.cc>
To:     linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Sascha Hauer <s.hauer@...gutronix.de>,
        Vladimir Oltean <olteanv@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Michael Walle <michael@...le.cc>
Subject: [PATCH] spi: fsl-dspi: use devm_spi_alloc_master()

Commit 530b5affc675 ("spi: fsl-dspi: fix use-after-free in remove path")
fixed the use-after-free by manually allocating memory. Nowadays, since
commit 5e844cc37a5c ("spi: Introduce device-managed SPI controller
allocation"), there is a devres version of spi_alloc_master() for exactly
this purpose. Revert the commit which introduced the manual allocation
and use the new devm_spi_alloc_master().

Signed-off-by: Michael Walle <michael@...le.cc>
---
Btw, using the devm_ version of spi_controller_register() doesn't seem to
be a good idea, see commit 8d559a64f00b ("spi: stm32: drop devres version
of spi_register_master").

 drivers/spi/spi-fsl-dspi.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index fd004c9db9dc..29f8a596c8ee 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -1227,17 +1227,11 @@ static int dspi_probe(struct platform_device *pdev)
 	void __iomem *base;
 	bool big_endian;
 
-	dspi = devm_kzalloc(&pdev->dev, sizeof(*dspi), GFP_KERNEL);
-	if (!dspi)
-		return -ENOMEM;
-
-	ctlr = spi_alloc_master(&pdev->dev, 0);
+	ctlr = devm_spi_alloc_master(&pdev->dev, sizeof(struct fsl_dspi));
 	if (!ctlr)
 		return -ENOMEM;
 
-	spi_controller_set_devdata(ctlr, dspi);
-	platform_set_drvdata(pdev, dspi);
-
+	dspi = spi_controller_get_devdata(ctlr);
 	dspi->pdev = pdev;
 	dspi->ctlr = ctlr;
 
@@ -1373,6 +1367,8 @@ static int dspi_probe(struct platform_device *pdev)
 	if (dspi->devtype_data->trans_mode != DSPI_DMA_MODE)
 		ctlr->ptp_sts_supported = true;
 
+	platform_set_drvdata(pdev, ctlr);
+
 	ret = spi_register_controller(ctlr);
 	if (ret != 0) {
 		dev_err(&pdev->dev, "Problem registering DSPI ctlr\n");
@@ -1396,7 +1392,8 @@ static int dspi_probe(struct platform_device *pdev)
 
 static int dspi_remove(struct platform_device *pdev)
 {
-	struct fsl_dspi *dspi = platform_get_drvdata(pdev);
+	struct spi_controller *ctlr = platform_get_drvdata(pdev);
+	struct fsl_dspi *dspi = spi_controller_get_devdata(ctlr);
 
 	/* Disconnect from the SPI framework */
 	spi_unregister_controller(dspi->ctlr);
-- 
2.30.2