linux-kernel - [PATCH 4.19 20/43] spi: pxa2xx: Fix use-after-free on unbind

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Message-Id: <20210115121958.030492373@linuxfoundation.org>
Date:   Fri, 15 Jan 2021 13:27:50 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
        Mark Brown <broonie@...nel.org>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 4.19 20/43] spi: pxa2xx: Fix use-after-free on unbind

From: Lukas Wunner <lukas@...ner.de>

commit 5626308bb94d9f930aa5f7c77327df4c6daa7759 upstream

pxa2xx_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/slave() helper
which keeps the private data accessible until the driver has unbound.

Fixes: 32e5b57232c0 ("spi: pxa2xx: Fix controller unregister order")
Signed-off-by: Lukas Wunner <lukas@...ner.de>
Cc: <stable@...r.kernel.org> # v2.6.17+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@...r.kernel.org> # v2.6.17+: 32e5b57232c0: spi: pxa2xx: Fix controller unregister order
Cc: <stable@...r.kernel.org> # v2.6.17+
Link: https://lore.kernel.org/r/5764b04d4a6e43069ebb7808f64c2f774ac6f193.1607286887.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@...nel.org>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/spi/spi-pxa2xx.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1572,7 +1572,7 @@ static int pxa2xx_spi_probe(struct platf
 		return -ENODEV;
 	}
 
-	master = spi_alloc_master(dev, sizeof(struct driver_data));
+	master = devm_spi_alloc_master(dev, sizeof(*drv_data));
 	if (!master) {
 		dev_err(&pdev->dev, "cannot alloc spi_master\n");
 		pxa_ssp_free(ssp);
@@ -1759,7 +1759,6 @@ out_error_dma_irq_alloc:
 	free_irq(ssp->irq, drv_data);
 
 out_error_master_alloc:
-	spi_controller_put(master);
 	pxa_ssp_free(ssp);
 	return status;
 }