Heap OSAL hangs if previous allocation has buffer overflow.  The design of the Heap OSAL uses a parameter called pxNextFreeBlock to essentially create a linked list of the buffers available.  However, if when writing to the previous free block allocation there is a buffer overflow, the next allocation will hang because the pxNextFreeBlock will have been overwritten.  This may require a redesign of the Heap OSAL given that this should not be susceptible to this type of error.