[PATCH] ACPICA: Add hard limit to while loop

[Alexey Starikovskiy <astarikovskiy@suse.de>]

We need to prevent infinite loops and lockups

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
---

 drivers/acpi/dispatcher/dsopcode.c |    9 +++++++--
 include/acpi/acstruct.h            |    1 +
 2 files changed, 8 insertions(+), 2 deletions(-)


diff --git a/drivers/acpi/dispatcher/dsopcode.c b/drivers/acpi/dispatcher/dsopcode.c
index 6a81c44..e2a3535 100644
--- a/drivers/acpi/dispatcher/dsopcode.c
+++ b/drivers/acpi/dispatcher/dsopcode.c
@@ -1246,8 +1246,13 @@ acpi_ds_exec_end_control_op(struct acpi_walk_state * walk_state,
 		if (walk_state->control_state->common.value) {
 
 			/* Predicate was true, go back and evaluate it again! */
-
-			status = AE_CTRL_PENDING;
+			/* Use hard limit to prevent infinite loops and lockups */
+			if (++walk_state->cycle_count > 0xFFFF) {
+				status = AE_LIMIT;
+				ACPI_ERROR ((AE_INFO, "Infinite loop detected"));
+			} else {
+				status = AE_CTRL_PENDING;
+			}
 		}
 
 		ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
diff --git a/include/acpi/acstruct.h b/include/acpi/acstruct.h
index 7980a26..fb4405e 100644
--- a/include/acpi/acstruct.h
+++ b/include/acpi/acstruct.h
@@ -94,6 +94,7 @@ struct acpi_walk_state {
 	u32 method_breakpoint;	/* For single stepping */
 	u32 user_breakpoint;	/* User AML breakpoint */
 	u32 parse_flags;
+	u32 cycle_count;	/* While loop cycle count */
 
 	struct acpi_parse_state parser_state;	/* Current state of parser */
 	u32 prev_arg_types;