heap_caps_malloc will fail to poison a block in IRAM with size not
divisible by 4. The proper fix will be to make poisoning code
smarter, or to disallow allocations from IRAM with size not aligned
by 4.
When realloc-ing to a smaller buffer size which ends up allocated in a different heap, the heap
structure is corrupted. This can only happen:
* If heap checking is Comprehensive (meaning buffers are never shrunk in place) and the heap the buffer was originally allocated in is full.
* Calling heap_caps_realloc() to deliberately move a buffer to a different capabilities type, and shrink it at the same time.
Probable fix for https://github.com/espressif/esp-idf/issues/1582
Probably the same issue:
https://www.esp32.com/viewtopic.php?f=2&t=4583https://www.esp32.com/viewtopic.php?f=13&t=3717
