FAILED: patch "[PATCH] spi: pxa2xx: Fix use-after-free on unbind" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-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 <[email protected]>.

thanks,

greg k-h

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

From 5626308bb94d9f930aa5f7c77327df4c6daa7759 Mon Sep 17 00:00:00 2001
From: Lukas Wunner <[email protected]>
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.

index 62a0f0f86553..bd2354fd438d 100644
@@ -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;
 }

Hi Greg,

Here is the backport, will also apply to 4.9-stable and 4.4-stable.

--
Regards
Sudip

From d0263dea6365ee31ca590e3866b8ca6a24cf456a Mon Sep 17 00:00:00 2001
From: Lukas Wunner <[email protected]>
Date: Mon, 7 Dec 2020 09:17:05 +0100
Subject: [PATCH] spi: pxa2xx: Fix use-after-free on unbind

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.

---
 drivers/spi/spi-pxa2xx.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index 1579eb2bc29f..06eb7d259b7f 100644
@@ -1660,7 +1660,7 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 		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);

@@ -1841,7 +1841,6 @@ static int pxa2xx_spi_probe(struct platform_device *pdev)
 	free_irq(ssp->irq, drv_data);
 
 out_error_master_alloc:
-	spi_master_put(master);
 	pxa_ssp_free(ssp);
 	return status;
 }

2.11.0

Thanks applied!

greg k-h