When the heap is exhausted (no free block), start and end markers are
the only blocks present in the free block list:
+---------------+ +-----------> NULL
| | |
| V |
+ ----- + + ----- +
| | | | | |
| | | | | |
+ ----- + + ----- +
xStart pxEnd
The code block which traverses the list of free blocks to calculate heap
stats used a do..while loop that moved past the end marker when the heap
had no free block resulting in a NULL pointer dereference. This commit
changes the do..while loop to while loop thereby ensuring that we never
move past the end marker.
This was reported here - https://github.com/FreeRTOS/FreeRTOS-Kernel/issues/534
Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
vApplicationMallocFailedHook was declared in each Heap file. which forces users to declare it and can cause problems if the prototype of the function changes.
Co-authored-by: Pierre-Noel Bouteville <pnb990@gmail.com>
Update the size calculations such that we only need to check for add
overflow only once. Also, change the way we detect add overflow so that
we do not need to cause an overflow to detect an overflow.
Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
We use the MSB of the size member of a BlockLink_t to track whether not
a block is allocated. Consequently, the size must not be so large that
the MSB is set. The check to see if the MSB in the size is set needs to
be done after the final size (metadata + alignment) is calculated.
Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
* Heap improvements
This commit makes the following improvements:
1. Add a check to heap_2 to track if a memory block is allocated to the
application or not. The MSB of the size field is used for this
purpose. The same check already exists in heap_4 and heap_5. This
check prevents against double free.
2. Add a new flag configHEAP_CLEAR_MEMORY_ON_FREE to heap_2, heap_4 and
heap_5. The application writer can set it to 1 in their
FreeRTOSConfig.h to ensure that a block of memory allocated using
pvPortMalloc is cleared (i.e. set to zero) when it is freed using
vPortFree. If left undefined, configHEAP_CLEAR_MEMORY_ON_FREE
defaults to 0 for backward compatibility. We recommend setting
configHEAP_CLEAR_MEMORY_ON_FREE to 1 for better security.
3. Add a new API pvPortCalloc to heap_2, heap_4 and heap_5. This API
has the following signature:
void * pvPortCalloc( size_t xNum, size_t xSize );
It allocates memory for an array of xNum objects each of which is of
xSize and initializes all bytes in the allocated storage to zero. If
allocation succeeds, it returns a pointer to the lowest byte in the
allocated memory block. On failure, it returns a null pointer.
Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>
The configuration was updated using
uncrustify -c .github/uncrustify.cfg -o .github/uncrustify.cfg --update-config-with-doc
to align with the actually used uncrustify version used, i.e., all
configuration is now explicitly set (and no longer implicit).
The files that are common to all ports ("portable/MemMang*" and
"portable/Common/mpu_wrappers.c" are now also autoformatted.
Co-authored-by: alfred gedeon <28123637+alfred2g@users.noreply.github.com>
* Style: Change FreeRTOS websites in comments
* Style: Change freertos to FreeRTOS in comments
* Style: Remove broken link
Co-authored-by: Alfred Gedeon <gedeonag@amazon.com>
