[PATCH] acpi: method: add more null pointer sanity checks on resource

[Colin King]

From: Colin Ian King <colin.king at canonical.com>

The pointer resource could possibly be null or even a garbage
value when it is dereferenced causing a segmentation fault, so
be extra vigilent, nullify it to start with and add a null
pointer check to avoid this.

Addresses-Coverity: ("Uninitialized pointer read")
Fixes: 2a377d8ec8c3 ("acpi: method: add _PTC test")
Signed-off-by: Colin Ian King <colin.king at canonical.com>
---
 src/acpi/method/method.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/acpi/method/method.c b/src/acpi/method/method.c
index 67a54465..37f6068d 100644
--- a/src/acpi/method/method.c
+++ b/src/acpi/method/method.c
@@ -2538,12 +2538,12 @@ static void method_test_PTC_return(
 		return;
 
 	for (i = 0; i < obj->Package.Count; i++) {
-		ACPI_RESOURCE *resource;
+		ACPI_RESOURCE *resource = NULL;
 		ACPI_STATUS   status;
 		ACPI_OBJECT *element_buf = &obj->Package.Elements[i];
 
 		status = AcpiBufferToResource(element_buf->Buffer.Pointer, element_buf->Buffer.Length, &resource);
-		if (ACPI_FAILURE(status)) {
+		if (ACPI_FAILURE(status) || !resource) {
 			failed = true;
 			fwts_failed(fw, LOG_LEVEL_HIGH,
 				"Method_PTCBadElement",
-- 
2.20.1