FAILED: patch "[PATCH] spi: pxa2xx: Fix use-after-free on unbind" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] spi: pxa2xx: Fix use-after-free on unbind" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-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 5626308bb94d9f930aa5f7c77327df4c6daa7759 Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@wunner.de>
Date: Mon, 7 Dec 2020 09:17:05 +0100
Subject: [PATCH] spi: pxa2xx: Fix use-after-free on unbind

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@wunner.de>
Cc: <stable@vger.kernel.org> # v2.6.17+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v2.6.17+: 32e5b57232c0: spi: pxa2xx: Fix controller unregister order
Cc: <stable@vger.kernel.org> # v2.6.17+
Link: https://lore.kernel.org/r/5764b04d4a6e43069ebb7808f64c2f774ac6f193.1607286887.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 62a0f0f86553..bd2354fd438d 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -1691,9 +1691,9 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	}
 
 	if (platform_info->is_slave)
-		controller = spi_alloc_slave(dev, sizeof(struct driver_data));
+		controller = devm_spi_alloc_slave(dev, sizeof(*drv_data));
 	else
-		controller = spi_alloc_master(dev, sizeof(struct driver_data));
+		controller = devm_spi_alloc_master(dev, sizeof(*drv_data));
 
 	if (!controller) {
 		dev_err(&pdev->dev, "cannot alloc spi_controller\n");
@@ -1916,7 +1916,6 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	free_irq(ssp->irq, drv_data);
 
 out_error_controller_alloc:
-	spi_controller_put(controller);
 	pxa_ssp_free(ssp);
 	return status;
 }