linux-kernel - [PATCH -next] Fix null pointer dereference in thermal

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Date:   Fri, 15 Oct 2021 08:32:30 +0000
From:   Yuanzheng Song <songyuanzheng@...wei.com>
To:     <rafael@...nel.org>, <daniel.lezcano@...aro.org>,
        <amitk@...nel.org>, <rui.zhang@...el.com>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH -next] Fix null pointer dereference in thermal_release()

If both dev_set_name() and device_register() failed, then
null pointer dereference occurs in thermal_release() which
will use strncmp() to compare the name.

So fix it by adding dev_set_name() return value check.

Signed-off-by: Yuanzheng Song <songyuanzheng@...wei.com>
---
 drivers/thermal/thermal_core.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 9e243d9f929e..6904b97fd6ea 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -904,6 +904,10 @@ __thermal_cooling_device_register(struct device_node *np,
 		goto out_kfree_cdev;
 	cdev->id = ret;
 
+	ret = dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
+	if (ret)
+		goto out_ida_remove;
+
 	cdev->type = kstrdup(type ? type : "", GFP_KERNEL);
 	if (!cdev->type) {
 		ret = -ENOMEM;
@@ -918,7 +922,6 @@ __thermal_cooling_device_register(struct device_node *np,
 	cdev->device.class = &thermal_class;
 	cdev->devdata = devdata;
 	thermal_cooling_device_setup_sysfs(cdev);
-	dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
 	ret = device_register(&cdev->device);
 	if (ret)
 		goto out_kfree_type;
@@ -1229,6 +1232,10 @@ thermal_zone_device_register(const char *type, int trips, int mask,
 	tz->id = id;
 	strlcpy(tz->type, type, sizeof(tz->type));
 
+	result = dev_set_name(&tz->device, "thermal_zone%d", tz->id);
+	if (result)
+		goto remove_id;
+
 	if (!ops->critical)
 		ops->critical = thermal_zone_device_critical;
 
@@ -1250,7 +1257,6 @@ thermal_zone_device_register(const char *type, int trips, int mask,
 	/* A new thermal zone needs to be updated anyway. */
 	atomic_set(&tz->need_update, 1);
 
-	dev_set_name(&tz->device, "thermal_zone%d", tz->id);
 	result = device_register(&tz->device);
 	if (result)
 		goto release_device;
-- 
2.25.1