ACPI: utils: Fix error path in acpi_evaluate_reference()

If a pointer to an uninitialized struct acpi_handle_list is passed to
acpi_evaluate_reference() and it decides to bail out early, either
because acpi_evaluate_object() fails, or because it produces invalid
data, the handles pointer from the struct acpi_handle_list will be
passed to kfree() and if it is not NULL, the kernel will crash on an
attempt to free unallocated memory.

Address this by moving the "end" label in acpi_evaluate_reference() to
the end of the function, which is sufficient, because no cleanup is
needed in that case.

Fixes: 2e57d10 ("ACPI: utils: Dynamically determine acpi_handle_list size")
Signed-off-by: Rafael J. Wysocki <[email protected]>
Tested-by: Woody Suwalski <[email protected]>

Author: rafaeljw

drivers/acpi/utils.c

@@ -399,13 +399,13 @@ acpi_evaluate_reference(acpi_handle handle,
 		acpi_handle_debug(list->handles[i], "Found in reference list\n");
 	}
 
-end:
 	if (ACPI_FAILURE(status)) {
 		list->count = 0;
 		kfree(list->handles);
 		list->handles = NULL;
 	}
 
+end:
 	kfree(buffer.pointer);
 
 	return status;