[PATCH] ACPICA: debugger: check status of acpi_evaluate_object in acpi_db_walk_for_fields

[Nikita Kiryushin]

Errors in acpi_evaluate_object can lead to incorrect state of buffer.
This can lead to access to data in previously ACPI_FREEd buffer and
secondary ACPI_FREE to the same buffer later.

Handle errors in acpi_evaluate_object the same way it is done earlier
with acpi_ns_handle_to_pathname.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 5fd033288a86 ("ACPICA: debugger: add command to dump all fields 
of particular subtype")
Signed-off-by: Nikita Kiryushin <kiryushin@xxxxxxxx>
---
 drivers/acpi/acpica/dbnames.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/acpica/dbnames.c b/drivers/acpi/acpica/dbnames.c
index b91155ea9c34..c9131259f717 100644
--- a/drivers/acpi/acpica/dbnames.c
+++ b/drivers/acpi/acpica/dbnames.c
@@ -550,8 +550,12 @@ acpi_db_walk_for_fields(acpi_handle obj_handle,
 	ACPI_FREE(buffer.pointer);
  	buffer.length = ACPI_ALLOCATE_LOCAL_BUFFER;
-	acpi_evaluate_object(obj_handle, NULL, NULL, &buffer);
-
+	status = acpi_evaluate_object(obj_handle, NULL, NULL, &buffer);
+	if (ACPI_FAILURE(status)) {
+		acpi_os_printf("Could Not evaluate object %p\n",
+			       obj_handle);
+		return (AE_OK);
+	}
 	/*
 	 * Since this is a field unit, surround the output in braces
 	 */
--
2.34.1