[PATCH] spi: oc-tiny: switch to managed controller allocation

[Fan Wu]

The controller is allocated with the non-managed spi_alloc_host() while
the interrupt is registered with devm_request_irq().  During removal,
spi_bitbang_stop() only unregisters the controller; the subsequent
spi_controller_put() then frees the controller together with its
embedded driver-private devdata, which is the IRQ handler's dev_id.  The
devm_request_irq() release action (free_irq()), which drains the
handler, does not run until after .remove() returns.  A late or latched
interrupt can therefore reach tiny_spi_irq() and dereference
already-freed memory (e.g. hw->base).

Switch to devm_spi_alloc_host() so that the devres LIFO order releases
the controller only after free_irq() has drained the handler, and drop
the now-redundant spi_controller_put() from .remove().  The probe error
path is simplified to direct returns.

This issue was found by an in-house static analysis tool.

Fixes: ce792580ea2c ("spi: add OpenCores tiny SPI driver")
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <fanwu01@xxxxxxxxxx>
---
 drivers/spi/spi-oc-tiny.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/spi/spi-oc-tiny.c b/drivers/spi/spi-oc-tiny.c
index 29333b1f82d7..1cd2a934c032 100644
--- a/drivers/spi/spi-oc-tiny.c
+++ b/drivers/spi/spi-oc-tiny.c
@@ -210,11 +210,11 @@ static int tiny_spi_probe(struct platform_device *pdev)
 	struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
 	struct tiny_spi *hw;
 	struct spi_controller *host;
-	int err = -ENODEV;
+	int err;
 
-	host = spi_alloc_host(&pdev->dev, sizeof(struct tiny_spi));
+	host = devm_spi_alloc_host(&pdev->dev, sizeof(struct tiny_spi));
 	if (!host)
-		return err;
+		return -ENOMEM;
 
 	/* setup the host state. */
 	host->bus_num = pdev->id;
@@ -232,10 +232,8 @@ static int tiny_spi_probe(struct platform_device *pdev)
 
 	/* find and map our resources */
 	hw->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(hw->base)) {
-		err = PTR_ERR(hw->base);
-		goto exit;
-	}
+	if (IS_ERR(hw->base))
+		return PTR_ERR(hw->base);
 	/* irq is optional */
 	hw->irq = platform_get_irq(pdev, 0);
 	if (hw->irq >= 0) {
@@ -243,7 +241,7 @@ static int tiny_spi_probe(struct platform_device *pdev)
 		err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
 				       pdev->name, hw);
 		if (err)
-			goto exit;
+			return err;
 	}
 	/* find platform data */
 	if (platp) {
@@ -252,29 +250,23 @@ static int tiny_spi_probe(struct platform_device *pdev)
 	} else {
 		err = tiny_spi_of_probe(pdev);
 		if (err)
-			goto exit;
+			return err;
 	}
 
 	/* register our spi controller */
 	err = spi_bitbang_start(&hw->bitbang);
 	if (err)
-		goto exit;
+		return err;
 	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 
 	return 0;
-
-exit:
-	spi_controller_put(host);
-	return err;
 }
 
 static void tiny_spi_remove(struct platform_device *pdev)
 {
 	struct tiny_spi *hw = platform_get_drvdata(pdev);
-	struct spi_controller *host = hw->bitbang.ctlr;
 
 	spi_bitbang_stop(&hw->bitbang);
-	spi_controller_put(host);
 }
 
 #ifdef CONFIG_OF
-- 
2.34.1