spi: Fixes for v7.0

There are two core fixes here.  One is from Johan dealing with an issue
 introduced by a devm_ API usage update causing things to be freed
 earlier than they had earlier when we fail to register a device, another
 from Danilo avoids unlocked acccess to data by converting to use a
 driver core API.
 
 We also have a few relatively minor driver specific fixes.
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Merge tag 'spi-fix-v7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi

Pull spi fixes from Mark Brown:
 "There are two core fixes here. One is from Johan dealing with an issue
  introduced by a devm_ API usage update causing things to be freed
  earlier than they had earlier when we fail to register a device,
  another from Danilo avoids unlocked acccess to data by converting to
  use a driver core API.

  We also have a few relatively minor driver specific fixes"

* tag 'spi-fix-v7.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: spi-fsl-lpspi: fix teardown order issue (UAF)
  spi: fix use-after-free on managed registration failure
  spi: use generic driver_override infrastructure
  spi: meson-spicc: Fix double-put in remove path
  spi: sn-f-ospi: Use devm_mutex_init() to simplify code
  spi: sn-f-ospi: Fix resource leak in f_ospi_probe()

drivers/spi/spi-fsl-lpspi.c

@@ -1009,7 +1009,7 @@ static int fsl_lpspi_probe(struct platform_device *pdev)
 		enable_irq(irq);
 	}
 
-	ret = devm_spi_register_controller(&pdev->dev, controller);
+	ret = spi_register_controller(controller);
 	if (ret < 0) {
 		dev_err_probe(&pdev->dev, ret, "spi_register_controller error\n");
 		goto free_dma;
@@ -1035,6 +1035,7 @@ static void fsl_lpspi_remove(struct platform_device *pdev)
 	struct fsl_lpspi_data *fsl_lpspi =
 				spi_controller_get_devdata(controller);
 
+	spi_unregister_controller(controller);
 	fsl_lpspi_dma_exit(controller);
 
 	pm_runtime_dont_use_autosuspend(fsl_lpspi->dev);

drivers/spi/spi-meson-spicc.c

@@ -1101,8 +1101,6 @@ static void meson_spicc_remove(struct platform_device *pdev)
 
 	/* Disable SPI */
 	writel(0, spicc->base + SPICC_CONREG);
-
-	spi_controller_put(spicc->host);
 }
 
 static const struct meson_spicc_data meson_spicc_gx_data = {

drivers/spi/spi-sn-f-ospi.c

@@ -612,7 +612,7 @@ static int f_ospi_probe(struct platform_device *pdev)
 	u32 num_cs = OSPI_NUM_CS;
 	int ret;
 
-	ctlr = spi_alloc_host(dev, sizeof(*ospi));
+	ctlr = devm_spi_alloc_host(dev, sizeof(*ospi));
 	if (!ctlr)
 		return -ENOMEM;
 
@@ -635,43 +635,22 @@ static int f_ospi_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, ospi);
 
 	ospi->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(ospi->base)) {
-		ret = PTR_ERR(ospi->base);
-		goto err_put_ctlr;
-	}
+	if (IS_ERR(ospi->base))
+		return PTR_ERR(ospi->base);
 
 	ospi->clk = devm_clk_get_enabled(dev, NULL);
-	if (IS_ERR(ospi->clk)) {
-		ret = PTR_ERR(ospi->clk);
-		goto err_put_ctlr;
-	}
+	if (IS_ERR(ospi->clk))
+		return PTR_ERR(ospi->clk);
 
-	mutex_init(&ospi->mlock);
+	ret = devm_mutex_init(dev, &ospi->mlock);
+	if (ret)
+		return ret;
 
 	ret = f_ospi_init(ospi);
 	if (ret)
-		goto err_destroy_mutex;
+		return ret;
 
-	ret = devm_spi_register_controller(dev, ctlr);
-	if (ret)
-		goto err_destroy_mutex;
-
-	return 0;
-
-err_destroy_mutex:
-	mutex_destroy(&ospi->mlock);
-
-err_put_ctlr:
-	spi_controller_put(ctlr);
-
-	return ret;
-}
-
-static void f_ospi_remove(struct platform_device *pdev)
-{
-	struct f_ospi *ospi = platform_get_drvdata(pdev);
-
-	mutex_destroy(&ospi->mlock);
+	return devm_spi_register_controller(dev, ctlr);
 }
 
 static const struct of_device_id f_ospi_dt_ids[] = {
@@ -686,7 +665,6 @@ static struct platform_driver f_ospi_driver = {
 		.of_match_table = f_ospi_dt_ids,
 	},
 	.probe = f_ospi_probe,
-	.remove = f_ospi_remove,
 };
 module_platform_driver(f_ospi_driver);
 

drivers/spi/spi.c

@@ -50,7 +50,6 @@ static void spidev_release(struct device *dev)
 	struct spi_device	*spi = to_spi_device(dev);
 
 	spi_controller_put(spi->controller);
-	kfree(spi->driver_override);
 	free_percpu(spi->pcpu_statistics);
 	kfree(spi);
 }
@@ -73,10 +72,9 @@ static ssize_t driver_override_store(struct device *dev,
 				     struct device_attribute *a,
 				     const char *buf, size_t count)
 {
-	struct spi_device *spi = to_spi_device(dev);
 	int ret;
 
-	ret = driver_set_override(dev, &spi->driver_override, buf, count);
+	ret = __device_set_driver_override(dev, buf, count);
 	if (ret)
 		return ret;
 
@@ -86,13 +84,8 @@ static ssize_t driver_override_store(struct device *dev,
 static ssize_t driver_override_show(struct device *dev,
 				    struct device_attribute *a, char *buf)
 {
-	const struct spi_device *spi = to_spi_device(dev);
-	ssize_t len;
-
-	device_lock(dev);
-	len = sysfs_emit(buf, "%s\n", spi->driver_override ? : "");
-	device_unlock(dev);
-	return len;
+	guard(spinlock)(&dev->driver_override.lock);
+	return sysfs_emit(buf, "%s\n", dev->driver_override.name ?: "");
 }
 static DEVICE_ATTR_RW(driver_override);
 
@@ -376,10 +369,12 @@ static int spi_match_device(struct device *dev, const struct device_driver *drv)
 {
 	const struct spi_device	*spi = to_spi_device(dev);
 	const struct spi_driver	*sdrv = to_spi_driver(drv);
+	int ret;
 
 	/* Check override first, and if set, only use the named driver */
-	if (spi->driver_override)
-		return strcmp(spi->driver_override, drv->name) == 0;
+	ret = device_match_driver_override(dev, drv);
+	if (ret >= 0)
+		return ret;
 
 	/* Attempt an OF style match */
 	if (of_driver_match_device(dev, drv))
@@ -3539,8 +3534,19 @@ int devm_spi_register_controller(struct device *dev,
 	if (ret)
 		return ret;
 
-	return devm_add_action_or_reset(dev, devm_spi_unregister_controller, ctlr);
+	/*
+	 * Prevent controller from being freed by spi_unregister_controller()
+	 * if devm_add_action_or_reset() fails for a non-devres allocated
+	 * controller.
+	 */
+	spi_controller_get(ctlr);
 
+	ret = devm_add_action_or_reset(dev, devm_spi_unregister_controller, ctlr);
+
+	if (ret == 0 || ctlr->devm_allocated)
+		spi_controller_put(ctlr);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(devm_spi_register_controller);
 

include/linux/spi/spi.h

@@ -159,10 +159,6 @@ extern void spi_transfer_cs_change_delay_exec(struct spi_message *msg,
  * @modalias: Name of the driver to use with this device, or an alias
  *	for that name.  This appears in the sysfs "modalias" attribute
  *	for driver coldplugging, and in uevents used for hotplugging
- * @driver_override: If the name of a driver is written to this attribute, then
- *	the device will bind to the named driver and only the named driver.
- *	Do not set directly, because core frees it; use driver_set_override() to
- *	set or clear it.
  * @pcpu_statistics: statistics for the spi_device
  * @word_delay: delay to be inserted between consecutive
  *	words of a transfer
@@ -224,7 +220,6 @@ struct spi_device {
 	void			*controller_state;
 	void			*controller_data;
 	char			modalias[SPI_NAME_SIZE];
-	const char		*driver_override;
 
 	/* The statistics */
 	struct spi_statistics __percpu	*pcpu_statistics;