linux-kernel - [PATCH 3.16 257/328] regulator: fix crash caused by null driver data

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Date:   Sun, 09 Dec 2018 21:50:33 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Yu Zhao" <yuzhao@...gle.com>,
        "Mark Brown" <broonie@...nel.org>
Subject: [PATCH 3.16 257/328] regulator: fix crash caused by null driver data

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Yu Zhao <yuzhao@...gle.com>

commit fb6de923ca3358a91525552b4907d4cb38730bdd upstream.

dev_set_drvdata() needs to be called before device_register()
exposes device to userspace. Otherwise kernel crashes after it
gets null pointer from dev_get_drvdata() when userspace tries
to access sysfs entries.

[Removed backtrace for length -- broonie]

Signed-off-by: Yu Zhao <yuzhao@...gle.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -3470,14 +3470,13 @@ regulator_register(const struct regulato
 	rdev->dev.parent = dev;
 	dev_set_name(&rdev->dev, "regulator.%d",
 		     atomic_inc_return(&regulator_no) - 1);
+	dev_set_drvdata(&rdev->dev, rdev);
 	ret = device_register(&rdev->dev);
 	if (ret != 0) {
 		put_device(&rdev->dev);
 		goto clean;
 	}
 
-	dev_set_drvdata(&rdev->dev, rdev);
-
 	if (config->ena_gpio && gpio_is_valid(config->ena_gpio)) {
 		ret = regulator_ena_gpio_request(rdev, config);
 		if (ret != 0) {