From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date: Mon, 13 Apr 2015 19:35:51 +0000 (+0200)
Subject: ACPI / scan: Fix NULL pointer dereference in acpi_companion_match()
X-Git-Tag: firefly_0821_release~176^2~1854^2^4~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5f2e3274e527ec52413b43b5a9b30422eda4cdd2;p=firefly-linux-kernel-4.4.55.git

ACPI / scan: Fix NULL pointer dereference in acpi_companion_match()

Commit e1acdeb0e770 "ACPI / scan: Simplify acpi_match_device()"
introduced code that may lead to a NULL pointer dereference when
trying to unlock a mutex.  Fix that.

Fixes: e1acdeb0e770 "ACPI / scan: Simplify acpi_match_device()"
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index d2e3c3e3f9c9..69bc0d888c01 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -247,6 +247,7 @@ static int create_of_modalias(struct acpi_device *acpi_dev, char *modalias,
 static struct acpi_device *acpi_companion_match(const struct device *dev)
 {
 	struct acpi_device *adev;
+	struct mutex *physical_node_lock;
 
 	adev = ACPI_COMPANION(dev);
 	if (!adev)
@@ -255,7 +256,8 @@ static struct acpi_device *acpi_companion_match(const struct device *dev)
 	if (list_empty(&adev->pnp.ids))
 		return NULL;
 
-	mutex_lock(&adev->physical_node_lock);
+	physical_node_lock = &adev->physical_node_lock;
+	mutex_lock(physical_node_lock);
 	if (list_empty(&adev->physical_node_list)) {
 		adev = NULL;
 	} else {
@@ -266,7 +268,7 @@ static struct acpi_device *acpi_companion_match(const struct device *dev)
 		if (node->dev != dev)
 			adev = NULL;
 	}
-	mutex_unlock(&adev->physical_node_lock);
+	mutex_unlock(physical_node_lock);
 
 	return adev;
 }