There are some cases that user use acpi_ns_walk_namespace() without checking acpi_disable flag. When acpi=off is provided in boot cmdline, acpi_gbl_root_node is NULL and calling acpi_ns_walk_namespace() will crash kernel. In order to avoid such misuse, we proactively check null ptr and return an error when we know ACPI is disabled. Signed-off-by: Tong Zhang <ztong0001@xxxxxxxxx> --- drivers/acpi/acpica/nswalk.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/acpi/acpica/nswalk.c b/drivers/acpi/acpica/nswalk.c index 915c2433463d..9ae45db16d86 100644 --- a/drivers/acpi/acpica/nswalk.c +++ b/drivers/acpi/acpica/nswalk.c @@ -171,6 +171,13 @@ acpi_ns_walk_namespace(acpi_object_type type, start_node = acpi_gbl_root_node; } + /* acpi_gbl_root_node is NULL when acpi=off is provided. + * We proactively check nulliness here and return an error if user call + * this function without checking acpi_disabled + */ + if (start_node == NULL) + return_ACPI_STATUS(AE_ERROR); + /* Null child means "get first node" */ parent_node = start_node; -- 2.25.1
