Update Tasks.c CBMC Proofs to Latest Code (#547)

* Fix Tasks.c patch, line numbers were out of sync and patching was
broken.
* Add assumption to TaskCreate proof that a task's priority is less than
the configured max.

With the introduction of
9efe10b805
an assertion is added to ensure a new task's priority is less than the
confirmed max. The CBMC proof for TaskCreate needs to include this assumption
in order to not assert and fail. Since this is now enforced in the code
we can add an assumption to the proof that a task must be created with a
priority smaller than the configured max.

FreeRTOS/Source

@@ -1 +1 @@
-Subproject commit 95433d02848af0d274648ae4cdd846f6eff76dde
+Subproject commit b08c19f74560dc8885eaf04c47483817d28e13e2

FreeRTOS/Test/CBMC/patches/0005-Remove-volatile-qualifier-from-tasks-variables.patch

@@ -40,21 +40,20 @@ Here, `uxPendedTicks` could return any value, making it impossible to unwind
 (or unroll) this loop in CBMC.  Therefore, we require `uxPendedTicks` to behave
 as a regular variable so that the loop can be unwound.
 
----
 diff --git a/FreeRTOS/Source/tasks.c b/FreeRTOS/Source/tasks.c
-index ff657733..8b57d198 100644
+index c7be57cb2..9f76465d5 100644
 --- a/FreeRTOS/Source/tasks.c
 +++ b/FreeRTOS/Source/tasks.c
-@@ -335,7 +335,7 @@ typedef tskTCB TCB_t;
+@@ -296,7 +296,7 @@ typedef struct tskTaskControlBlock       /* The old naming convention is used to
  
- /*lint -save -e956 A manual analysis and inspection has been used to determine
-  * which static variables must be declared volatile. */
--PRIVILEGED_DATA TCB_t * volatile pxCurrentTCB = NULL;
-+PRIVILEGED_DATA TCB_t * pxCurrentTCB = NULL;
- 
- /* Lists for ready and blocked tasks. --------------------
-  * xDelayedTaskList1 and xDelayedTaskList2 could be move to function scople but
-@@ -344,8 +344,8 @@ PRIVILEGED_DATA TCB_t * volatile pxCurrentTCB = NULL;
+     #if ( configUSE_NEWLIB_REENTRANT == 1 )
+         /* Allocate a Newlib reent structure that is specific to this task.
+-         * Note Newlib support has been included by popular demand, but is not
++          Note Newlib support has been included by popular demand, but is not
+          * used by the FreeRTOS maintainers themselves.  FreeRTOS is not
+          * responsible for resulting newlib operation.  User must be familiar with
+          * newlib and must provide system-wide implementations of the necessary
+@@ -343,8 +343,8 @@ PRIVILEGED_DATA TCB_t * volatile pxCurrentTCB = NULL;
  PRIVILEGED_DATA static List_t pxReadyTasksLists[ configMAX_PRIORITIES ]; /*< Prioritised ready tasks. */
  PRIVILEGED_DATA static List_t xDelayedTaskList1;                         /*< Delayed tasks. */
  PRIVILEGED_DATA static List_t xDelayedTaskList2;                         /*< Delayed tasks (two lists are used - one for delays that have overflowed the current tick count. */
@@ -65,7 +64,7 @@ index ff657733..8b57d198 100644
  PRIVILEGED_DATA static List_t xPendingReadyList;                         /*< Tasks that have been readied while the scheduler was suspended.  They will be moved to the ready list when the scheduler is resumed. */
  
  #if ( INCLUDE_vTaskDelete == 1 )
-@@ -372,7 +372,7 @@ PRIVILEGED_DATA static volatile UBaseType_t uxCurrentNumberOfTasks = ( UBaseType
+@@ -371,7 +371,7 @@ PRIVILEGED_DATA static volatile UBaseType_t uxCurrentNumberOfTasks = ( UBaseType
  PRIVILEGED_DATA static volatile TickType_t xTickCount = ( TickType_t ) configINITIAL_TICK_COUNT;
  PRIVILEGED_DATA static volatile UBaseType_t uxTopReadyPriority = tskIDLE_PRIORITY;
  PRIVILEGED_DATA static volatile BaseType_t xSchedulerRunning = pdFALSE;

FreeRTOS/Test/CBMC/proofs/Task/TaskCreate/TaskCreate_harness.c

@@ -1,29 +1,27 @@
 /*
- * FreeRTOS memory safety proofs with CBMC.
- * Copyright (C) 2019 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ * FreeRTOS V202012.00
+ * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
- * Permission is hereby granted, free of charge, to any person
- * obtaining a copy of this software and associated documentation
- * files (the "Software"), to deal in the Software without
- * restriction, including without limitation the rights to use, copy,
- * modify, merge, publish, distribute, sublicense, and/or sell copies
- * of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
  *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
  *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
- * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
- * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
  *
- * http://aws.amazon.com/freertos
- * http://www.FreeRTOS.org
  */
 
 #include <stdint.h>
@@ -44,9 +42,11 @@ void harness()
 	char * pcName;
 	configSTACK_DEPTH_TYPE usStackDepth = STACK_DEPTH;
 	void * pvParameters;
-	UBaseType_t uxPriority;
 	TaskHandle_t * pxCreatedTask;
 
+	UBaseType_t uxPriority;
+    __CPROVER_assume( uxPriority < configMAX_PRIORITIES );
+
 	vNondetSetCurrentTCB();
 	vSetGlobalVariables();
 	vPrepareTaskLists();