From b5020cb3d8be05ecb45019a9196fe6c3b2ac3a38 Mon Sep 17 00:00:00 2001 From: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com> Date: Mon, 7 Dec 2020 09:53:22 -0800 Subject: [PATCH 1/4] Prevent unprivileged task from altering MPU configuration (#227) This change removes the FreeRTOS System Calls (aka MPU wrappers) for the following kernel APIs: - xTaskCreateRestricted - xTaskCreateRestrictedStatic - vTaskAllocateMPURegions A system call allows an unprivileged task to execute a kernel API which is otherwise accessible to privileged software only. The above 3 APIs can create a new task with a different MPU configuration or alter the MPU configuration of an existing task. This an be (mis)used by an unprivileged task to grant itself access to a region which it does not have access to. Removing the system calls for these APIs ensures that an unprivileged task cannot execute this APIs. If an unprivileged task attempts to execute any of these API, it will result in a Memory Fault. Signed-off-by: Gaurav Aggarwal --- include/mpu_prototypes.h | 6 ------ include/mpu_wrappers.h | 2 -- portable/Common/mpu_wrappers.c | 38 ---------------------------------- 3 files changed, 46 deletions(-) diff --git a/include/mpu_prototypes.h b/include/mpu_prototypes.h index 81b1bf845..62601d2f1 100644 --- a/include/mpu_prototypes.h +++ b/include/mpu_prototypes.h @@ -50,12 +50,6 @@ TaskHandle_t MPU_xTaskCreateStatic( TaskFunction_t pxTaskCode, UBaseType_t uxPriority, StackType_t * const puxStackBuffer, StaticTask_t * const pxTaskBuffer ) FREERTOS_SYSTEM_CALL; -BaseType_t MPU_xTaskCreateRestricted( const TaskParameters_t * const pxTaskDefinition, - TaskHandle_t * pxCreatedTask ) FREERTOS_SYSTEM_CALL; -BaseType_t MPU_xTaskCreateRestrictedStatic( const TaskParameters_t * const pxTaskDefinition, - TaskHandle_t * pxCreatedTask ) FREERTOS_SYSTEM_CALL; -void MPU_vTaskAllocateMPURegions( TaskHandle_t xTask, - const MemoryRegion_t * const pxRegions ) FREERTOS_SYSTEM_CALL; void MPU_vTaskDelete( TaskHandle_t xTaskToDelete ) FREERTOS_SYSTEM_CALL; void MPU_vTaskDelay( const TickType_t xTicksToDelay ) FREERTOS_SYSTEM_CALL; BaseType_t MPU_xTaskDelayUntil( TickType_t * const pxPreviousWakeTime, diff --git a/include/mpu_wrappers.h b/include/mpu_wrappers.h index 18fce4daf..cdc34b094 100644 --- a/include/mpu_wrappers.h +++ b/include/mpu_wrappers.h @@ -47,8 +47,6 @@ /* Map standard tasks.h API functions to the MPU equivalents. */ #define xTaskCreate MPU_xTaskCreate #define xTaskCreateStatic MPU_xTaskCreateStatic - #define xTaskCreateRestricted MPU_xTaskCreateRestricted - #define vTaskAllocateMPURegions MPU_vTaskAllocateMPURegions #define vTaskDelete MPU_vTaskDelete #define vTaskDelay MPU_vTaskDelay #define xTaskDelayUntil MPU_xTaskDelayUntil diff --git a/portable/Common/mpu_wrappers.c b/portable/Common/mpu_wrappers.c index 1b6696b6f..2bcabb5cc 100644 --- a/portable/Common/mpu_wrappers.c +++ b/portable/Common/mpu_wrappers.c @@ -85,34 +85,6 @@ void vPortResetPrivilege( BaseType_t xRunningPrivileged ) } /*-----------------------------------------------------------*/ -#if ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) - BaseType_t MPU_xTaskCreateRestricted( const TaskParameters_t * const pxTaskDefinition, - TaskHandle_t * pxCreatedTask ) /* FREERTOS_SYSTEM_CALL */ - { - BaseType_t xReturn; - BaseType_t xRunningPrivileged = xPortRaisePrivilege(); - - xReturn = xTaskCreateRestricted( pxTaskDefinition, pxCreatedTask ); - vPortResetPrivilege( xRunningPrivileged ); - return xReturn; - } -#endif /* conifgSUPPORT_DYNAMIC_ALLOCATION */ -/*-----------------------------------------------------------*/ - -#if ( configSUPPORT_STATIC_ALLOCATION == 1 ) - BaseType_t MPU_xTaskCreateRestrictedStatic( const TaskParameters_t * const pxTaskDefinition, - TaskHandle_t * pxCreatedTask ) /* FREERTOS_SYSTEM_CALL */ - { - BaseType_t xReturn; - BaseType_t xRunningPrivileged = xPortRaisePrivilege(); - - xReturn = xTaskCreateRestrictedStatic( pxTaskDefinition, pxCreatedTask ); - vPortResetPrivilege( xRunningPrivileged ); - return xReturn; - } -#endif /* conifgSUPPORT_DYNAMIC_ALLOCATION */ -/*-----------------------------------------------------------*/ - #if ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) BaseType_t MPU_xTaskCreate( TaskFunction_t pvTaskCode, const char * const pcName, @@ -150,16 +122,6 @@ void vPortResetPrivilege( BaseType_t xRunningPrivileged ) #endif /* configSUPPORT_STATIC_ALLOCATION */ /*-----------------------------------------------------------*/ -void MPU_vTaskAllocateMPURegions( TaskHandle_t xTask, - const MemoryRegion_t * const xRegions ) /* FREERTOS_SYSTEM_CALL */ -{ - BaseType_t xRunningPrivileged = xPortRaisePrivilege(); - - vTaskAllocateMPURegions( xTask, xRegions ); - vPortResetPrivilege( xRunningPrivileged ); -} -/*-----------------------------------------------------------*/ - #if ( INCLUDE_vTaskDelete == 1 ) void MPU_vTaskDelete( TaskHandle_t pxTaskToDelete ) /* FREERTOS_SYSTEM_CALL */ { From c7a9a01c94987082b223d3e59969ede64363da63 Mon Sep 17 00:00:00 2001 From: Cobus van Eeden <35851496+cobusve@users.noreply.github.com> Date: Mon, 7 Dec 2020 10:36:27 -0800 Subject: [PATCH 2/4] Improve heap2 bounds checking (#224) * Improve heap bounds checking in pvPortMalloc --- portable/MemMang/heap_1.c | 19 +++++++++++++------ portable/MemMang/heap_2.c | 24 +++++++++++++++++------- portable/MemMang/heap_4.c | 32 ++++++++++++++++++++------------ portable/MemMang/heap_5.c | 25 ++++++++++++++++--------- 4 files changed, 66 insertions(+), 34 deletions(-) diff --git a/portable/MemMang/heap_1.c b/portable/MemMang/heap_1.c index 4a7f8c2e5..2b7346340 100644 --- a/portable/MemMang/heap_1.c +++ b/portable/MemMang/heap_1.c @@ -22,7 +22,6 @@ * https://www.FreeRTOS.org * https://github.com/FreeRTOS * - * 1 tab == 4 spaces! */ @@ -72,13 +71,20 @@ void * pvPortMalloc( size_t xWantedSize ) void * pvReturn = NULL; static uint8_t * pucAlignedHeap = NULL; - /* Ensure that blocks are always aligned to the required number of bytes. */ + /* Ensure that blocks are always aligned. */ #if ( portBYTE_ALIGNMENT != 1 ) { if( xWantedSize & portBYTE_ALIGNMENT_MASK ) { - /* Byte alignment required. */ - xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ); + /* Byte alignment required. Check for overflow. */ + if ( (xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) )) > xWantedSize ) + { + xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ); + } + else + { + xWantedSize = 0; + } } } #endif @@ -91,8 +97,9 @@ void * pvPortMalloc( size_t xWantedSize ) pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) & ucHeap[ portBYTE_ALIGNMENT ] ) & ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) ); } - /* Check there is enough room left for the allocation. */ - if( ( ( xNextFreeByte + xWantedSize ) < configADJUSTED_HEAP_SIZE ) && + /* Check there is enough room left for the allocation and. */ + if( ( xWantedSize > 0 ) && /* valid size */ + ( ( xNextFreeByte + xWantedSize ) < configADJUSTED_HEAP_SIZE ) && ( ( xNextFreeByte + xWantedSize ) > xNextFreeByte ) ) /* Check for overflow. */ { /* Return the next free byte then increment the index past this diff --git a/portable/MemMang/heap_2.c b/portable/MemMang/heap_2.c index 640cd54fd..e132ae3ea 100644 --- a/portable/MemMang/heap_2.c +++ b/portable/MemMang/heap_2.c @@ -22,7 +22,6 @@ * https://www.FreeRTOS.org * https://github.com/FreeRTOS * - * 1 tab == 4 spaces! */ /* @@ -132,21 +131,32 @@ void * pvPortMalloc( size_t xWantedSize ) xHeapHasBeenInitialised = pdTRUE; } - /* The wanted size is increased so it can contain a BlockLink_t + /* The wanted size must be increased so it can contain a BlockLink_t * structure in addition to the requested amount of bytes. */ - if( xWantedSize > 0 ) + if( ( xWantedSize > 0 ) && + ( ( xWantedSize + heapSTRUCT_SIZE ) > xWantedSize ) ) /* Overflow check */ { xWantedSize += heapSTRUCT_SIZE; - /* Ensure that blocks are always aligned to the required number of bytes. */ - if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0 ) + /* Byte alignment required. Check for overflow. */ + if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) ) + > xWantedSize ) { - /* Byte alignment required. */ xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ); + configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 ); } + else + { + xWantedSize = 0; + } + } + else + { + xWantedSize = 0; } - if( ( xWantedSize > 0 ) && ( xWantedSize < configADJUSTED_HEAP_SIZE ) ) + + if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) ) { /* Blocks are stored in byte order - traverse the list from the start * (smallest) block until one of adequate size is found. */ diff --git a/portable/MemMang/heap_4.c b/portable/MemMang/heap_4.c index 7e5357ccf..2a1ee20ff 100644 --- a/portable/MemMang/heap_4.c +++ b/portable/MemMang/heap_4.c @@ -136,34 +136,42 @@ void * pvPortMalloc( size_t xWantedSize ) * kernel, so it must be free. */ if( ( xWantedSize & xBlockAllocatedBit ) == 0 ) { - /* The wanted size is increased so it can contain a BlockLink_t + /* The wanted size must be increased so it can contain a BlockLink_t * structure in addition to the requested amount of bytes. */ - if( xWantedSize > 0 ) + if( ( xWantedSize > 0 ) && + ( ( xWantedSize + xHeapStructSize ) > xWantedSize ) ) /* Overflow check */ { xWantedSize += xHeapStructSize; - /* Ensure that blocks are always aligned to the required number - * of bytes. */ + /* Ensure that blocks are always aligned. */ if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 ) { - /* Byte alignment required. */ - xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ); - configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 ); + /* Byte alignment required. Check for overflow. */ + if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) ) + > xWantedSize ) + { + xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ); + configASSERT( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) == 0 ); + } + else + { + xWantedSize = 0; + } } else { mtCOVERAGE_TEST_MARKER(); } - } - else + } + else { - mtCOVERAGE_TEST_MARKER(); + xWantedSize = 0; } if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) ) { /* Traverse the list from the start (lowest address) block until - * one of adequate size is found. */ + * one of adequate size is found. */ pxPreviousBlock = &xStart; pxBlock = xStart.pxNextFreeBlock; @@ -174,7 +182,7 @@ void * pvPortMalloc( size_t xWantedSize ) } /* If the end marker was reached then a block of adequate size - * was not found. */ + * was not found. */ if( pxBlock != pxEnd ) { /* Return the memory space pointed to - jumping over the diff --git a/portable/MemMang/heap_5.c b/portable/MemMang/heap_5.c index 90c0b5bdf..fe194a6a0 100644 --- a/portable/MemMang/heap_5.c +++ b/portable/MemMang/heap_5.c @@ -22,7 +22,6 @@ * https://www.FreeRTOS.org * https://github.com/FreeRTOS * - * 1 tab == 4 spaces! */ /* @@ -150,16 +149,24 @@ void * pvPortMalloc( size_t xWantedSize ) { /* The wanted size is increased so it can contain a BlockLink_t * structure in addition to the requested amount of bytes. */ - if( xWantedSize > 0 ) + if( ( xWantedSize > 0 ) && + ( ( xWantedSize + xHeapStructSize ) > xWantedSize ) ) /* Overflow check */ { xWantedSize += xHeapStructSize; - /* Ensure that blocks are always aligned to the required number - * of bytes. */ + /* Ensure that blocks are always aligned */ if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 ) { - /* Byte alignment required. */ - xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ); + /* Byte alignment required. Check for overflow */ + if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) ) > + xWantedSize ) + { + xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ); + } + else + { + xWantedSize = 0; + } } else { @@ -168,13 +175,13 @@ void * pvPortMalloc( size_t xWantedSize ) } else { - mtCOVERAGE_TEST_MARKER(); + xWantedSize = 0; } if( ( xWantedSize > 0 ) && ( xWantedSize <= xFreeBytesRemaining ) ) { /* Traverse the list from the start (lowest address) block until - * one of adequate size is found. */ + * one of adequate size is found. */ pxPreviousBlock = &xStart; pxBlock = xStart.pxNextFreeBlock; @@ -185,7 +192,7 @@ void * pvPortMalloc( size_t xWantedSize ) } /* If the end marker was reached then a block of adequate size - * was not found. */ + * was not found. */ if( pxBlock != pxEnd ) { /* Return the memory space pointed to - jumping over the From d05b9c123f2bf9090bce386a244fc934ae44db5b Mon Sep 17 00:00:00 2001 From: Cobus van Eeden <35851496+cobusve@users.noreply.github.com> Date: Mon, 7 Dec 2020 11:07:31 -0800 Subject: [PATCH 3/4] Add addition overflow check for stream buffer (#226) --- stream_buffer.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/stream_buffer.c b/stream_buffer.c index 03cfc0615..fec03a781 100644 --- a/stream_buffer.c +++ b/stream_buffer.c @@ -258,8 +258,16 @@ static void prvInitialiseNewStreamBuffer( StreamBuffer_t * const pxStreamBuffer, * this is a quirk of the implementation that means otherwise the free * space would be reported as one byte smaller than would be logically * expected. */ - xBufferSizeBytes++; - pucAllocatedMemory = ( uint8_t * ) pvPortMalloc( xBufferSizeBytes + sizeof( StreamBuffer_t ) ); /*lint !e9079 malloc() only returns void*. */ + if( xBufferSizeBytes < ( xBufferSizeBytes + 1 + sizeof( StreamBuffer_t ) ) ) + { + xBufferSizeBytes++; + pucAllocatedMemory = ( uint8_t * ) pvPortMalloc( xBufferSizeBytes + sizeof( StreamBuffer_t ) ); /*lint !e9079 malloc() only returns void*. */ + } + else + { + pucAllocatedMemory = NULL; + } + if( pucAllocatedMemory != NULL ) { From 47338393f1f79558f6144213409f09f81d7c4837 Mon Sep 17 00:00:00 2001 From: Cobus van Eeden <35851496+cobusve@users.noreply.github.com> Date: Mon, 7 Dec 2020 11:48:51 -0800 Subject: [PATCH 4/4] add assert for addition overflow on queue creation (#225) --- queue.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/queue.c b/queue.c index d2e27e55a..b01dfd11f 100644 --- a/queue.c +++ b/queue.c @@ -397,6 +397,9 @@ BaseType_t xQueueGenericReset( QueueHandle_t xQueue, /* Check for multiplication overflow. */ configASSERT( ( uxItemSize == 0 ) || ( uxQueueLength == ( xQueueSizeInBytes / uxItemSize ) ) ); + /* Check for addition overflow. */ + configASSERT( ( sizeof( Queue_t ) + xQueueSizeInBytes ) > xQueueSizeInBytes ); + /* Allocate the queue and storage area. Justification for MISRA * deviation as follows: pvPortMalloc() always ensures returned memory * blocks are aligned per the requirements of the MCU stack. In this case